MHHS explained: what half-hourly settlement changes for UK businesses

Market-wide Half-Hourly Settlement, usually shortened to MHHS, is changing how almost every electricity supply point in Great Britain is settled.

The reform moves the industry away from allocating much of a customer’s consumption through broad, predetermined profiles.

Suppliers will instead be settled for each half-hour using actual interval data where it is available, with new load-shaping and estimation methods where it is not.

For a business, the most important points are:

• MHHS changes electricity settlement, not automatically the retail tariff or invoice frequency.
• A migrated MPAN can remain on a single-rate fixed contract.
• Most businesses do not need to apply for migration.
• Migration does not always require a meter replacement.
• A traditional meter does not become a communicating smart meter merely because its MPAN enters MHHS.
• Suppliers may use a site’s real load shape more directly when pricing future contracts.
• Time-of-use tariffs and flexibility products may become more widely available, but they can cost more for a peak-heavy business as well as less for a flexible one.
• Existing MOP, Data Collector and Data Aggregator arrangements need to transition carefully so that services continue and duplicate charges do not arise.

Permanent migration began in October 2025. On 5 August 2026, the MHHS Programme reported that 50% of industry MPANs had migrated. The current programme deadline for completing migration is 7 May 2027.

MHHS is a Great Britain electricity-market reform. It covers England, Scotland and Wales. Northern Ireland operates within the separate Single Electricity Market and is not part of the GB programme.

This guide explains settlement in plain English, the current timetable, which meters are affected, what happens to bills and tariffs, how MOP and data contracts change, and what a business should check before and after its MPAN migrates.

Programme dates, market rules and official statistics last reviewed: 10 August 2026. This is general information, not a prediction of an individual supplier’s tariff or a substitute for reviewing the signed energy, metering and data-service contracts.

MHHS at a glance

Question	Current answer
What does MHHS stand for?	Market-wide Half-Hourly Settlement
What is changing?	Suppliers are being settled for electricity in each half-hour using actual interval data where available and new estimation or load-shaping methods where it is not
Where does it apply?	Great Britain: England, Scotland and Wales
Does it apply in Northern Ireland?	No; Northern Ireland participates in the separate Single Electricity Market
Does it apply to gas?	No; MHHS concerns electricity settlement
Does every business have to apply?	No; the registered supplier normally manages MPAN migration
Does every meter need replacing?	No; many suitable smart and advanced meters can remain in place
Does MHHS guarantee actual half-hourly readings?	No; traditional meters and data gaps can still require calculated or estimated half-hourly values
Will a business be billed every half-hour?	Not necessarily; settlement granularity and invoice frequency are different matters
Is a time-of-use tariff compulsory?	No; a migrated MPAN can still have a single-rate contract
Does the MPAN change?	The 13-digit MPAN core normally remains the supply-point identifier
When did migration start?	M11 and M12 were approved on 21 October 2025, with migration commencing from 22 October 2025
Current migration position	The programme reported 50% of industry MPANs migrated by 5 August 2026
M14	28 October 2026: supplier qualification and service-readiness milestone
M15	7 May 2027: migration-completion deadline
M16	2 July 2027: programme milestone for cutover to the faster settlement timetable, delivered through staged timetable changes
Main business opportunity	Better load data, more targeted tariffs and greater value from flexible demand, batteries, solar and managed EV charging
Main business risk	Peak-heavy consumption, data errors or poorly coordinated metering contracts can increase cost or create disruption

The definitive delivery dates are maintained on the MHHS Programme milestone page. Older articles may still quote the original October 2025 completion date from Ofgem’s 2021 decision. That date was superseded by the current programme schedule and should not be used as the migration-completion deadline.

What does MHHS mean?

MHHS means that electricity suppliers are settled against consumption or export allocated to individual half-hour periods across the retail market.

“Settlement” is the industry process for comparing:

• The electricity a supplier bought or contracted to buy
• The electricity attributed to its customers in each settlement period
• The resulting imbalance, reconciliation and payment position

Elexon administers the Balancing and Settlement Code, which contains the rules for this process in Great Britain. Its MHHS overview describes the reform as one of the largest changes to the retail electricity market since competition began.

The process sits behind the customer-facing energy contract. It is possible for the supplier to be settled using half-hourly values while the business continues to receive:

• One monthly invoice
• One fixed unit rate
• One standing charge
• A conventional annual-consumption forecast

Therefore, these statements are not equivalent:

• The MPAN is settled half-hourly.
• The customer pays a different retail price in every half-hour.

The first describes the industry settlement method. The second describes a particular time-of-use or dynamic tariff. MHHS enables suppliers to design more tariffs of that kind, but does not place every business on one.

Why does electricity need to be settled?

Electricity is generated and consumed continuously. Suppliers buy energy in advance, but their customers’ actual demand will not match those purchases perfectly.

Settlement calculates the difference.

For example, suppose a supplier expected its customers to use 100MWh during a half-hour but the settled volume was 108MWh. The supplier is short by 8MWh for that period. If the settled volume were 95MWh, it would be long by 5MWh.

The financial consequence depends on the wider balancing arrangements, not on this simplified example alone. The important point is that the supplier’s cost can change according to when electricity is used, not only the total number of kWh used over a month.

Ofgem’s explanation of moving to half-hourly settlement notes that settlement creates an incentive for suppliers to buy energy to meet demand in each half-hour. Accurate interval data allows that responsibility to follow customers’ actual consumption more closely.

What happened before MHHS?

Under the legacy non-half-hourly system, many smaller sites did not provide actual readings for every settlement period.

Instead, the industry used information including:

• Periodic cumulative meter readings
• Estimated Annual Consumption, or EAC
• Annualised Advance, or AA
• Profile Class
• Standard Settlement Configuration, or SSC
• Time Pattern Regime, or TPR
• National load-profile samples

A profile distributed the site’s total consumption across half-hours using the expected shape for a broad customer group. That meant two businesses with the same annual consumption and classification could be assigned similar settlement shapes even if one used most electricity in the morning and the other operated late at night.

The method was necessary when frequent interval data was not widely available. It is less suitable for an electricity system containing millions of smart meters, solar exports, electric vehicles, batteries and flexible loads.

Larger sites have used actual half-hourly settlement for many years. Ofgem’s P272 guidance for businesses explains that businesses in legacy Profile Classes 5 to 8 with advanced meters were required to move to half-hourly settlement from 1 April 2017. Legacy Profile Class 00 supplies were also already half-hourly settled.

MHHS extends a new half-hourly model across the wider market rather than limiting it to large, advanced or voluntarily elected sites.

Legacy settlement versus MHHS

Area	Legacy position	MHHS position for a migrated MPAN
Settlement granularity	Many smaller sites allocated through non-half-hourly profiling	Every MPAN enters a half-hourly settlement model
Actual interval data	Used for established HH sites; not available for many NHH sites	Used where a smart or advanced meter and communications make it available
Traditional meters	Period reads fed profile-based NHH settlement	Register advances are converted into half-hourly values using new load shapes
Profiling	Broad legacy Profile Classes and national profile samples	More granular load shapes calculated from actual data under the Load Shaping Service
Metering roles	Meter Operator Agent, HH/NHH Data Collector and Data Aggregator	Metering Service and Smart, Advanced or Unmetered Data Services, with central market-wide processing
Data transfer	Many legacy DTC flows and appointed agents	Many interactions use the Data Integration Platform and new interfaces
Final reconciliation	Approximately 14 months under the legacy timetable	Scheduled to move to four months through the staged M16 transition
Retail tariff	Fixed, multi-rate or flexible according to the contract	Still fixed, multi-rate or flexible according to the contract; MHHS does not dictate it

Moving to half-hourly settlement removes the continuing need for the old profiling service. Elexon has explained that its Profile Administration Service is being decommissioned as MHHS is implemented.

This does not mean every legacy code disappears from every bill immediately. During transition, old and new data must coexist, and invoice templates may retain familiar fields. The MPAN core remains more reliable than assuming an old profile-class field tells the complete settlement story.

The MHHS migration timetable

The current timetable contains several programme milestones rather than one single switch-over date.

Milestone	Date	What it means
M10	24 September 2025	Central systems became ready for migration and operation
M13	24 September 2025	The Load Shaping Service was switched on
M11	22 October 2025	Migration began for Advanced and Unmetered MPANs following approval on 21 October
M12	22 October 2025	Migration began for Smart and Non-Smart metered MPANs following approval on 21 October
M14	28 October 2026	Suppliers are expected to be MHHS-qualified and able to operate under the Target Operating Model
M15	7 May 2027	Suppliers must complete migration of their MPANs, subject to the programme’s formal exception processes
M16	2 July 2027	Cutover milestone for the new settlement timetable

M11 and M12 opened an approximately 18-month migration period. Individual MPANs move in supplier-planned batches, so two premises supplied by the same company can have different migration dates.

By early August 2026, the programme said half of all industry MPANs had migrated. This is a portfolio-level statistic; it does not prove that a particular business MPAN has moved.

What happens at M14?

M14 is primarily an industry-readiness deadline. Suppliers need the qualifications, systems and active services required to accept and operate migrated MPANs under the new model.

It is not the date on which every remaining customer automatically receives a new tariff or meter.

It is also the programme’s “one-way gate”. From M14, a migrated MPAN cannot be moved back into the legacy non-half-hourly regime when the customer changes supplier, and new registrations must follow the MHHS route. Before M14, a migrated MPAN can be reverse-migrated in defined circumstances where the gaining supplier is not yet MHHS-qualified.

The rules create consequences where a supplier is not appropriately qualified. The precise effect can depend on its market-participant identifiers and an approved retirement plan, so a customer should avoid turning the milestone into a simple claim that every non-compliant supplier immediately stops trading.

For business procurement, the practical question is whether the proposed supplier can register and support the specific MPAN, market segment, Metering Service and Data Service after the relevant dates.

What happens at M15?

M15 is the migration-completion deadline of 7 May 2027.

Ofgem approved BSC Modification P487, under which a supplier that fails to complete migration by M15 can be restricted from registering new customers until it completes migration, unless the formal exemption process applies.

The measure is directed at suppliers. It does not create a new penalty payable by an individual business whose MPAN is difficult to migrate.

What happens at M16?

M16 concerns the move to the faster settlement timetable. The implementation is staged rather than an instantaneous change to every process on one day.

The programme’s M16 timetable page currently sets out:

• Final Reconciliation, or RF, moving from 14 to seven months for settlement days from 1 October 2026
• RF moving from seven to four months for settlement days from 1 April 2027
• Initial Settlement, or SF, moving from 15 to seven working days for settlement days from 1 July 2027
• First Reconciliation, or R1, moving to 29 working days for settlement days from 1 October 2027
• A Post Final, or DF, run at 20 months for settlement days from 1 October 2027

The page also identifies readiness decision points. These dates should therefore be described as the current programme design, not as a reason to assume every future gate is unconditional.

Which businesses are covered?

MHHS covers import- and export-related MPANs across the Great Britain electricity retail market.

It therefore affects electricity supplies used by:

• Sole traders and microbusinesses
• Shops, pubs, cafés and restaurants
• Offices and professional services
• Warehouses and logistics operators
• Farms and rural enterprises
• Factories and industrial sites
• Hotels, care homes and leisure facilities
• Schools, universities and public bodies
• Hospitals and healthcare premises
• Data centres and communications sites
• Landlords and managing agents
• Solar, battery and other small-generation exporters
• Unmetered supplies such as street lighting and traffic equipment

The route and consumer-facing effect differ by meter type, contract and market segment.

Does MHHS apply to Northern Ireland?

No. Elexon’s Balancing and Settlement Code concerns the electricity system in Great Britain. Northern Ireland participates with Ireland in the Single Electricity Market, which has separate rules, identifiers, metering roles and settlement processes.

A company with premises on both sides of the Irish Sea should not apply GB migration dates or MPAN terminology to its Northern Irish accounts.

Does MHHS apply to gas?

No. MHHS is an electricity reform. It does not change gas meters, MPRNs, gas settlement or gas tariffs.

A dual-fuel business can therefore see a change to the electricity account’s industry arrangements while its gas account remains unaffected.

The three MHHS market segments

The new model groups MPANs into three broad market segments.

Market segment	Typical arrangement	Main data route
Smart	Smart meters served through the DCC, plus traditional or non-smart meters within the Smart and Non-Smart model	Smart Data Service
Advanced	Advanced and AMR-type meters, including many larger commercial installations	Advanced Data Service
Unmetered Supplies	Approved unmetered equipment such as street lights, signs and some street furniture	Unmetered Supplies Data Service

The segment is an industry classification. It should not be inferred solely from the customer-facing description “smart meter”, “AMR” or “half-hourly meter” on a sales proposal.

The meter type, connection type, registration data and appointed services need to agree.

Traditional equipment has not disappeared. The government’s smart-meter statistics to the end of 2025, which cover electricity and gas meters at smaller non-domestic sites, reported 2.1 million smart and advanced meters, equal to 67% of that meter population. It also reported that smart meters operating in smart mode plus advanced meters represented 64% of all non-domestic meters. These are smart-rollout figures rather than an MHHS migration count, but they show why the settlement design still needs to support traditional and non-communicating equipment.

How different meter types are treated

Smart meters operating in smart mode

A communicating smart electricity meter can record interval consumption and make it available through the smart-meter communications infrastructure.

For settlement, the Smart Data Service retrieves, validates, estimates where necessary and submits period-level values under the relevant rules.

This creates the clearest route to actual half-hourly settlement, but a smart meter can still have:

• Temporary communications gaps
• Missing intervals
• Incorrect technical details
• Commissioning problems
• A wrong meter serial number linked to the account
• A period in which estimates are required

“Smart” does not mean every value will always be actual or that the customer’s bill can never be wrong.

Advanced and AMR meters

Advanced meters are common at medium and large non-domestic sites. Many already record half-hourly channels and transmit them to a legacy Half-Hourly Data Collector.

After migration, the applicable Advanced Data Service handles data collection and processing. The metering appointment normally becomes Metering Service Advanced.

An established half-hourly business may notice little physical change. The larger change is behind the scenes:

• New market roles
• New data interfaces
• New appointment records
• Central market-wide processing
• A shorter settlement timetable

Communications, channel configuration, current-transformer ratios and complex-site details remain important. MHHS does not correct inaccurate technical data automatically.

Smart meters operating in traditional mode

A smart meter can be installed but unable to communicate in smart mode. It may then behave operationally more like a traditional meter for part of the process.

Where actual settlement-period data cannot be obtained, the Data Service can use register information and the applicable estimation method. The business should continue to provide reads when asked and should not assume that the presence of a smart-meter casing guarantees complete interval data.

Traditional meters

A traditional meter can be migrated without suddenly gaining communications or recording a separate actual reading for every half-hour.

The Smart Data Service uses valid cumulative register readings to calculate the consumption between reads, then allocates it to settlement periods using the applicable load shape. The MHHS Design Q&A explains that the Smart Data Service recovers reads for traditional meters and determines half-hourly consumption from them.

This is still half-hourly settlement, but it is not the same quality of evidence as actual interval data from a communicating meter.

Regular accurate reads remain valuable because they anchor the total consumption that is distributed across the load shape.

Unmetered supplies

An approved unmetered supply does not have a conventional meter at every item. Consumption is calculated using information such as:

• Equipment inventory
• Charge codes
• Wattage
• Operating hours
• Switch regimes
• Dimming or variable-power schedules

The Unmetered Supplies Data Service produces settlement data under the new arrangements. Councils and infrastructure operators should make sure inventories, switching regimes and equipment changes remain accurate.

Does MHHS require a new meter?

Not automatically.

Migration is principally a change to registration, appointments, data flows and settlement treatment. A physical exchange may be unnecessary where the existing meter:

• Has the required functionality
• Is correctly registered
• Has compatible communications
• Has accurate technical details
• Is supported by the relevant Metering and Data Services

A replacement or site visit may still be needed where:

• The meter is obsolete or faulty
• Communications cannot be restored
• The meter cannot provide the required data
• Technical details are missing or inconsistent
• A current-transformer arrangement is incorrectly recorded
• The site is complex and existing records are inadequate
• Import and export configuration is wrong
• The supplier’s smart-meter obligations require an exchange independently of MHHS

One current transition issue concerns traditional meters recorded on current-transformer connections. The programme has required suppliers and metering parties to identify and remediate affected MPANs, which can involve correcting the connection record or replacing the meter with a suitable advanced meter. Elexon is also progressing CP1628 on traditional meters at CT connections.

If a supplier requests access, the business should ask for the reason, proposed work, outage requirement, price and responsible party. It should not refuse automatically: unresolved site data can prevent clean migration and later create billing problems.

What is the Load Shaping Service?

The Load Shaping Service, or LSS, creates representative half-hourly shapes using actual data from relevant smart and advanced meters.

These shapes are more granular than the old profile-class method. Depending on the category, they can reflect factors including:

• Region or Grid Supply Point Group
• Domestic or non-domestic status
• Import or export
• Connection type
• Switched-load characteristics
• Time of day and day type
• Actual conditions on the settlement date

For a traditional meter, the load shape distributes the metered advance across individual periods.

Suppose a valid pair of readings shows that a business used 700kWh in a week. The settlement process still needs to decide how much belongs in every half-hour. The relevant load shape provides the proportions, which are scaled so that the half-hourly values add back to 700kWh.

This is more responsive than giving every similar customer one fixed historical shape, but it is still not the business’s actual interval pattern. A site with unusual working hours may therefore benefit from a communicating smart or advanced meter even though its traditional meter can technically be migrated.

What is the Target Operating Model?

The Target Operating Model, or TOM, is the collection of services, responsibilities, data flows and settlement arrangements used under MHHS.

The main roles relevant to a business are:

Role or service	What it does	What the customer should understand
Electricity supplier	Buys energy, contracts with the customer, registers the MPAN, appoints services and issues bills	The supplier normally controls the formal industry appointments
Metering Service Advanced, or MSA	Installs, commissions, maintains and documents advanced-meter arrangements	Commercially, providers may still call this a MOP service
Metering Service Smart, or MSS	Provides the applicable metering service for Smart and Traditional arrangements	It is distinct from the Smart Data Service
Advanced Data Service, or ADS	Retrieves, validates, estimates and submits advanced-meter data	Broadly succeeds much of the legacy HH Data Collector function for migrated Advanced MPANs
Smart Data Service, or SDS	Processes data for Smart and Traditional arrangements	Uses actual smart data where available and register-read/load-shape methods for traditional meters
Unmetered Supplies Data Service, or UMSDS	Produces data for approved unmetered supplies	Important to street-lighting and infrastructure portfolios
Load Shaping Service, or LSS	Calculates load shapes from actual data	Supports traditional-meter allocation and estimation
Market-wide Data Service, or MDS	Performs central period-level processing and produces market-wide settlement volumes	Replaces part of the old decentralised aggregation structure
Volume Allocation Service, or VAS	Uses the processed volumes within Supplier Volume Allocation	A central BSC service rather than a customer-appointed provider
Data Integration Platform, or DIP	Carries standardised messages between authorised market participants	It is not a customer energy portal

The technical detail is set out in Elexon’s live procedures for the Smart Data Service, Advanced Data Service and central MHHS services.

What happens to MOP, DC and DA contracts?

MHHS changes the formal industry roles, but it does not automatically cancel a customer’s commercial contracts.

Under the legacy model:

• The Meter Operator Agent dealt with the physical meter and technical records.
• The Half-Hourly or Non-Half-Hourly Data Collector retrieved and validated data.
• The Data Aggregator combined validated data for settlement.

For a migrated MPAN:

Legacy description	Broad MHHS replacement
Meter Operator Agent	Metering Service Advanced or Metering Service Smart
Half-Hourly Data Collector	Advanced Data Service for an Advanced-segment MPAN
Non-Half-Hourly Data Collector	Smart/Traditional processing through the Smart Data Service model
Customer-appointed Data Aggregator	Central market-wide processing replaces the old appointment structure
Legacy DTC data flows	Many messages move through the Data Integration Platform

This is a practical mapping, not a one-for-one legal equivalence for every specialist site.

Smaller businesses

For many small sites, the supplier arranges metering and data services and recovers the cost through the electricity price or standing charge. The customer may not hold any separate MOP or Data Collector agreement.

The supplier normally manages the transition.

The business should nevertheless check that:

• Automatic reads continue
• The first migrated bills are sensible
• No unexpected metering line is added
• A requested site appointment is genuine
• A smart meter remains in smart mode

Larger half-hourly businesses

Larger businesses frequently hold direct MOP, DC/DA, communications or data-portal contracts.

They should not cancel a legacy agreement merely because an MPAN has migrated. First establish:

1. The contractual end date and notice period.
2. Which legacy roles are included.
3. Which MHHS roles the provider is qualified to perform.
4. The effective date of the new formal appointment.
5. Whether the existing agreement is amended, novated or interpreted under a change-in-law clause.
6. When each legacy charge stops.
7. When each replacement charge begins.
8. Whether portal and API access continue.
9. Who resolves a failed appointment or migration message.
10. Whether a customer-direct contract indicator and the active appointment both show the intended provider.

The supplier still controls the formal industry appointment. A contract signed between the business and a metering company does not, by itself, make that company the active Metering Service or Data Service in market records.

Read the full MOP contracts, Data Collector and Data Aggregator guide before renewing or terminating a direct arrangement.

Can MHHS cause duplicate charges?

It can create an opportunity for overlapping commercial costs if contracts and appointments are poorly coordinated.

For example:

• A direct MOP continues invoicing under a five-year agreement.
• The supplier appoints its default Metering Service after migration.
• A separate Data Service charge appears in the supply price.
• The old DC/DA provider continues to invoice because no valid termination notice was given.

These are not automatically four charges for the same work. They can cover different assets, periods or functions. Compare:

• MPAN
• Service role
• Effective date
• Appointed provider
• Contracting party
• Asset rental
• Communications
• Portal or API
• VAT period

Where a genuine overlap exists, correct both the invoice and the industry appointment. Fixing only the bill can leave the wrong party responsible for the meter or data.

Will MHHS change business electricity bills?

Not automatically on the migration date.

The supplier can continue billing the customer under the existing contract. If the contract specifies one fixed unit rate, the presence of half-hourly settlement does not on its own rewrite that price.

MHHS can affect bills indirectly through:

• More accurate consumption allocation
• More frequent actual data
• Supplier pricing at renewal
• New time-of-use products
• Changed metering or data-service charges
• Corrections to previously inaccurate technical data
• Different treatment of peak-heavy load in a bespoke quotation
• Improved identification of waste, maximum demand and out-of-hours use

Any price change must still have a contractual basis. Check the supply agreement for:

• Fixed versus pass-through charges
• Change-in-law provisions
• Metering and data-service clauses
• Profile or volume tolerance provisions
• Reforecasting rights
• Time-band definitions
• Indexation
• Renewal terms

If a supplier says MHHS requires an immediate additional fee, ask it to identify the exact clause, MPAN, service and effective date.

Will businesses have to use time-of-use tariffs?

No.

A supplier can settle a site half-hourly while charging a flat retail rate. MHHS is expected to encourage more products that reflect the changing cost of electricity during the day, but product design remains a commercial decision.

Business tariffs can include:

Tariff type	How the consumption price works	Main consideration
Single-rate fixed	One unit price during the contracted period	Simple, but gives no direct reward for shifting load
Static time-of-use	Predetermined peak, shoulder and off-peak prices	Useful where operations can move into cheaper bands
Dynamic time-of-use	Prices can change daily or by settlement period	Greater opportunity and volatility; requires active management
Flexible procurement	Wholesale energy bought in tranches, with pass-through or shape exposure	Suits larger users with governance and market expertise
Indexed	Price follows a stated market index or formula	Transparent formula but potentially volatile
Demand-response or flexibility product	Payment or saving for changing load when requested	Requires reliable measurement, operational control and clear baseline rules

The correct comparison uses the site’s interval profile, not one advertised headline rate.

Worked example: why load shape matters

Consider a business using 100,000kWh per year. It compares:

• A flat rate of 22p/kWh
• An illustrative time-of-use tariff charging 30p/kWh in peak periods and 16p/kWh off peak

Standing charges, VAT, CCL, network charges and metering costs are excluded so that only the shape effect is shown.

Consumption shape	Peak use	Off-peak use	Flat-rate cost	Time-of-use cost	Difference from flat
Flexible profile	40,000kWh	60,000kWh	£22,000	£21,600	£400 saving
Peak-heavy profile	70,000kWh	30,000kWh	£22,000	£25,800	£3,800 extra
Peak-heavy site after shifting 20,000kWh	50,000kWh	50,000kWh	£22,000	£23,000	£1,000 extra

The load shift saves the business:

20,000kWh × (30p − 16p) = £2,800 per year

However, the shifted time-of-use profile still costs £1,000 more than the illustrative flat tariff. This is why “we can move some load” is not enough to prove that a time-of-use contract is cheaper.

The complete calculation is:

Annual variable cost = sum of each half-hour’s kWh × the rate for that half-hour

Then add:

• Standing charges
• Metering and data costs
• Capacity charges
• Relevant network charges
• Supplier fees and margin
• CCL
• VAT
• Finance or technology costs needed to shift demand

Run the model over at least a complete year. A winter peak, summer shutdown, weekend operation or seasonal production cycle can make one month’s profile misleading.

Will a peak-heavy business pay more?

Not necessarily under its current contract, but its load shape can become more commercially visible.

Suppliers already consider consumption patterns when pricing many half-hourly sites. MHHS makes interval settlement standard across the market and can allow pricing and forecasting to become more granular for smaller businesses as well.

A site may look more expensive to serve where it uses a high share of electricity during:

• System-wide demand peaks
• Expensive wholesale periods
• Restricted network periods
• Hours with volatile imbalance exposure

A site may be more attractive where it:

• Operates overnight
• Can delay EV charging
• Can pre-cool or pre-heat safely
• Uses batteries to avoid expensive periods
• Has controllable pumps, motors or HVAC
• Exports electricity when it is valuable
• Can participate in flexibility services

This does not mean suppliers will all use one standard peak formula. Each quotation can use different wholesale curves, risk allowances, network assumptions and margin.

Which bill charges does MHHS not automatically change?

MHHS does not itself abolish or reset:

• The standing charge
• Climate Change Levy
• VAT
• Agreed supply capacity or maximum import capacity
• Excess-capacity charges
• Reactive-power charges
• Meter asset rental
• A direct MOP contract
• Network charges such as DUoS or TNUoS
• BSUoS recovery
• Renewable and low-carbon policy costs
• An existing fixed unit rate

These items can still change under their own rules, annual charging statements or contract terms. A supplier may also recover them differently in a future tariff.

Read the business energy bill guide to separate settlement changes from taxes, metering, capacity and network costs.

What changes for businesses already settled half-hourly?

The customer-facing impact can be smaller for an established half-hourly site.

Such a site may already have:

• An advanced or Code of Practice meter
• A Meter Operator
• A Half-Hourly Data Collector
• A Data Aggregator
• Remote communications
• Half-hourly consumption files
• Capacity and reactive-power invoice lines
• A bespoke load-shaped supply price

MHHS can still change:

• The formal Metering Service role
• The Data Service appointment
• The message formats and identifiers
• The route through which data reaches settlement
• Central aggregation
• The settlement timetable
• The contract wording used by metering providers

Do not assume “we were already HH” means no work is required. Procurement, energy, finance and facilities teams should identify who owns every current agent contract and who will verify the post-migration appointments.

How can a business tell whether its MPAN has migrated?

There may be no obvious physical sign.

Possible evidence includes:

• Written confirmation from the supplier
• Confirmation from the MOP or Data Service
• An authorised industry record showing the MHHS indicator and market segment
• New Metering Service or Data Service identifiers
• A change in data messages or portal labels
• A supplier quotation that identifies the MPAN as migrated

The 13-digit MPAN core normally remains unchanged. The meter serial number also remains unchanged unless the physical meter is exchanged.

Do not rely solely on:

• The appearance of the meter
• A legacy Profile Class shown on an old invoice
• The fact that an invoice contains one unit rate
• Whether the bill says “smart”
• Whether another site with the same supplier has migrated

Ask the supplier for the status of the specific MPAN and the effective migration date.

Does Profile Class 00 still prove a site is half-hourly?

Profile Class 00 was the familiar legacy identifier for traditional half-hourly supplies. Profile Classes 5 to 8 identified many advanced-meter sites before P272.

Under MHHS, legacy profile-based settlement loses its central role. Registration and settlement use new fields such as market segment, connection type, meter group and consumption component class.

During transition, old profile-class and SSC data can remain in systems or appear on documents. Therefore:

• A historic 00 still provides useful context about the old arrangement.
• A non-00 value does not prove that a migrated MPAN is still non-half-hourly settled.
• The MPAN core remains valid.
• Current market-segment and appointment data are more informative after migration.

This is one reason older guides that tell every business to identify half-hourly settlement solely from the two digits at the top of the “S-number” are becoming unreliable.

Will invoices become more accurate?

They can, but MHHS does not eliminate billing errors.

Actual interval data can reduce reliance on estimated monthly reads and make consumption allocation more precise. The business can also identify anomalies sooner.

Errors can still arise from:

• Missing smart communications
• Invalid or rejected intervals
• A wrong multiplier
• An incorrect current-transformer ratio
• Crossed meters
• A meter exchange not being recorded
• Incorrect energisation status
• A wrong import or export relationship
• Failed service appointments
• A supplier using different billing data from the settlement data
• Estimated values not being replaced promptly
• A tariff mapped to the wrong time bands

Settlement data and billing data are related, but they are not necessarily identical at every point in time. A supplier can retrieve data separately for billing and later reconcile it with the settlement service.

When checking the first bills after migration, compare:

1. MPAN core.
2. Meter serial number.
3. Billing dates.
4. Total kWh.
5. Actual versus estimated indicators.
6. Meter multiplier and CT ratio where relevant.
7. Time bands and unit rates.
8. Standing-charge days.
9. Metering and data-service charges.
10. Credits or rebills for earlier periods.

Does the four-month settlement timetable limit back-billing?

No.

The scheduled four-month Final Reconciliation timetable is an industry settlement deadline. It is not a four-month limit on:

• A supplier issuing a customer invoice
• A business disputing a bill
• Contractual audit rights
• Ofgem’s back-billing protection
• Court limitation periods

Post-final settlement processes and formal disputes can also exist after the normal Final Reconciliation point.

Customer-facing recovery is governed separately by the supply licence, contract and general law. Eligible businesses can have 12-month protection in specified circumstances, but exceptions and business-size rules matter. Read the detailed guide to business energy back-billing rather than treating M16 as a substitute.

The faster timetable still increases the operational value of early action. A business should report a missing read, wrong meter or abnormal profile promptly so the supplier and Data Service can correct it before settlement positions harden.

Data access and privacy

Half-hourly data can reveal more about operating patterns than one monthly reading. It may show:

• Opening and closing times
• Weekend or night operation
• Production cycles
• Equipment start-up peaks
• Seasonal shutdowns
• On-site generation
• EV charging schedules
• Occupancy patterns

Suppliers and market participants remain subject to data-protection law and the restrictions attached to the purpose for which data is obtained.

Microbusiness data rules

Ofgem modified Standard Licence Condition 47 to support MHHS. Its SLC 47 decision distinguishes between “old system” and “new system” customers.

In simplified terms:

Microbusiness category	Settlement-data position
Old system customer	Half-hourly processing is the default, but the customer can retain a route to object and move to monthly processing, subject to the licence conditions
New system customer	Half-hourly consumption data is processed for settlement by default with no microbusiness opt-out

A new system customer broadly includes a microbusiness whose remote-access or smart meter was installed after the new framework took effect, or one that later entered a new contract, excluding specified cases such as a deemed contract.

The legal definitions and exceptions should be checked before advising a particular customer. Changing supplier or positively entering a new contract can affect the category.

Where a microbusiness has agreed a tariff calculated from half-hourly data, it cannot use a settlement-data objection to keep the tariff while preventing the data processing needed to operate it.

The special SLC 47 microbusiness framework should not be assumed to provide the same opt-out to a larger non-domestic customer.

Export data

Ofgem’s framework requires half-hourly data for relevant registered exports without the domestic or microbusiness opt-out that can apply to some import consumption.

This matters where the business has:

• Solar PV
• A battery
• Wind or hydro generation
• A Smart Export Guarantee arrangement
• A private-wire or power-purchase agreement

Import and export MPANs should be checked separately.

Can a business access the DIP?

Not simply because it is the customer.

The Data Integration Platform is an industry message-exchange service for authorised participants. It is not a public dashboard and does not replace the customer’s supplier or metering portal.

Commercial data access should be specified separately, including:

• Raw versus validated values
• Actual versus estimated flags
• Frequency and latency
• Time zone
• File format
• API rights
• Historic retention
• Portfolio access
• Rights after changing provider

A settlement Data Service can perform its market function without supplying the customer with a polished analytics portal. Conversely, a portal can display data without being the formal Data Service.

What happens when a business switches supplier?

MHHS does not prevent competition or normal switching, but the gaining supplier must be able to support the MPAN’s current arrangements.

During the transition, a switch can interact with:

• The MPAN’s migration date
• Old and new agent appointments
• Opening and closing reads
• Direct MOP or data contracts
• The customer-direct Metering Service record
• Import/export relationships
• A microbusiness’s old-system or new-system data category

Before agreeing a contract, ask the gaining supplier:

1. Is this MPAN already migrated?
2. Which market segment applies?
3. Can you retain our chosen Metering Service and Data Service?
4. Which identifiers do you need from the provider?
5. Will you add default metering or data charges?
6. How will opening data be agreed?
7. Will our portal or API continue?
8. Does the tariff use actual half-hourly shape data?
9. What happens if migration and the switch are scheduled together?
10. Who owns resolution if an appointment fails?

A direct MOP agreement usually survives a change of electricity supplier unless its own terms say otherwise. Tell the gaining supplier about it before the switch.

Import, export, solar and batteries

MHHS covers both import- and export-related MPANs, which supports more accurate treatment of distributed generation and flexible assets.

Solar PV

Half-hourly import and export data can distinguish:

• Solar generation used behind the meter
• Grid imports when demand exceeds generation
• Surplus electricity exported
• Curtailment or zero-export periods

The generation meter, import meter and export MPAN can represent different things. Do not assume one data feed contains all three.

Battery storage

A battery can:

• Charge in low-price periods
• Discharge during expensive periods
• Reduce site peak demand
• store surplus solar
• Provide flexibility services

The financial model must include efficiency losses, degradation, capacity limits, finance, export restrictions and the tariff’s exact price windows.

Electric vehicles

Managed charging is one of the clearest flexible loads. A fleet can potentially move significant consumption away from expensive hours without changing total mileage.

Operational constraints still control the decision:

• Vehicle return time
• Required departure state of charge
• Charger capacity
• Site import capacity
• Simultaneous charging
• Driver behaviour
• Resilience requirements

MHHS provides the settlement foundation; it does not install chargers, increase the site’s connection capacity or guarantee a flexibility payment.

How can different business types respond?

Business type	Possible MHHS opportunity	Main risk to test
Office	Move EV charging, hot-water heating and some HVAC load	Strong weekday morning and late-afternoon peaks
Retail	Optimise refrigeration, lighting and charging across a portfolio	Trading hours may overlap expensive periods
Restaurant or pub	Pre-cooling and daytime preparation	Evening peak demand can be difficult to shift
Hotel	Control laundry, water heating, HVAC and battery schedules	Guest comfort and continuous demand limit flexibility
Factory	Stagger motors, compressors, furnaces and production batches	Production losses can outweigh energy savings
Cold store	Pre-cool within safe temperature limits and use thermal inertia	Food safety and equipment cycling constraints
Warehouse	Schedule charging, conveyors and HVAC	Low base load can make a large solar system export-heavy
Farm	Time pumps, refrigeration, grain drying and charging	Seasonal demand and network limitations
Care home	Optimise non-critical loads and hot water	Safeguarding and resilience take priority
School or college	Control heating, ventilation and on-site generation	Holidays can create surplus solar and unusual profiles
EV fleet depot	Managed charging and possible flexibility services	Departure deadlines and connection capacity
Data centre	Battery and cooling optimisation	Reliability obligations and continuous high load
Multi-site group	Compare load shapes and negotiate portfolio products	Missing MPANs, inconsistent data and mixed migration status

No business should move a safety-critical or production-critical process merely to capture a small tariff difference. The operational cost of failure belongs in the model.

How to prepare for MHHS

1. Build an MPAN register

For every electricity supply, record:

1. MPAN core
2. Site address
3. Meter serial number
4. Import or export
5. Supplier
6. Meter type
7. Connection type
8. Current MOP or Metering Service
9. Current DC/DA or Data Service
10. Direct-contract status
11. Contract end date
12. Notice deadline
13. Known MHHS migration status and date

Do not merge related import and export MPANs into one row.

2. Obtain interval data

Ask for at least 12 months and preferably 24 months where operations are seasonal.

Check:

1. Whether every period is present
2. Actual and estimated flags
3. Units
4. Time zone and daylight-saving treatment
5. Meter multiplier
6. Duplicate timestamps
7. Negative values
8. Import and export direction
9. Site closures or abnormal periods

For a traditional meter, genuine site-level interval data may not exist. In that case, record that limitation rather than treating settlement-shaped values as measured truth.

3. Establish the current load shape

Calculate:

• Total annual kWh
• Day and night proportions
• Weekday and weekend proportions
• Highest half-hourly demand
• Seasonal peaks
• Base load when the site is closed
• Potentially flexible kWh
• Solar self-consumption and export
• EV charging demand

The objective is to separate consumption that is technically movable from consumption that is merely inconvenient to move.

4. Review metering contracts

List every direct agreement for:

• MOP or Metering Service
• DC/DA or Data Service
• Meter asset rental
• Communications
• Data portal
• API
• Analytics software
• Maintenance and callouts

Obtain written confirmation of how each service transitions under MHHS.

5. Test future tariffs

Run each quote against the same interval dataset.

Include:

• All time bands
• Weekends and bank holidays
• Seasonal rate changes
• Negative or capped prices where relevant
• Standing charges
• Capacity
• Network pass-through
• Metering and data
• Supplier fees
• CCL and VAT
• Expected load-shifting costs

Use a downside case as well as the sales forecast.

6. Monitor the first migrated period

After confirmation of migration:

• Download the first available data
• Compare total kWh with the meter and bill
• Check appointment continuity
• Check actual/estimated flags
• Confirm portal and API access
• Look for duplicate service charges
• Confirm import and export are not reversed
• Investigate unusual peaks

Keep screenshots, files and correspondence. Early evidence makes a later dispute easier to reconstruct.

Questions to ask an electricity supplier

1. Has each MPAN migrated to MHHS?
2. What is the effective migration date?
3. Which market segment applies?
4. Which Metering Service and Data Service are appointed?
5. Is the meter communicating and providing actual period data?
6. What happens when data is missing?
7. Does migration change any charge under our current contract?
8. Which clause permits that change?
9. Is our tariff flat, static time-of-use, dynamic or pass-through?
10. Which time zone and time bands are used for billing?
11. Can we download actual and estimated flags?
12. How much history is retained?
13. Will our direct metering provider be retained after a switch?
14. Are import and export MPANs both in scope?
15. Who resolves a failed migration or appointment?

Questions to ask a MOP or data provider

1. Are you qualified for MSA, MSS, ADS or SDS as applicable?
2. What are your Market Participant and DIP identifiers?
3. Which role applies to each MPAN before and after migration?
4. When do legacy DC/DA charges stop?
5. When do MHHS charges begin?
6. Does the contract permit a price change?
7. Will the service term restart?
8. Will the existing meter be adopted or exchanged?
9. Does communications hardware remain supported?
10. Will the portal and API continue?
11. Are values raw, validated or settlement-ready?
12. How are missing intervals flagged and corrected?
13. Who maintains the customer-direct contract record?
14. Does that record match the active appointment?
15. What happens when the customer switches supplier?

Common MHHS misconceptions

“Every business will receive a new smart meter”

False. Many MPANs migrate using their existing meter. Traditional meters can be settled through register readings and load shapes, although some sites need remediation or replacement.

“Every business will pay 48 different prices each day”

False. Settlement is half-hourly; the retail tariff can remain single-rate.

“A migrated traditional meter produces actual half-hourly data”

False. The Data Service can create settlement-period values from cumulative reads and load shapes. Those values are calculated, not measured in every period.

“MHHS abolishes the MOP contract”

False. The formal role changes to a Metering Service for migrated MPANs, but customer contracts, asset rental and service charges do not vanish automatically.

“Profile Class 00 is the only way to identify half-hourly settlement”

False under the new model. Profile Class is a legacy indicator and can remain on documents during transition. Check the current MHHS status and market segment.

“The four-month timetable means a supplier cannot rebill after four months”

False. Settlement reconciliation and customer back-billing are separate legal and contractual issues.

“MHHS guarantees a lower bill”

False. Ofgem expects system-wide benefits and innovation, but an individual result depends on load shape, tariff, data quality and operating flexibility.

“The DIP gives the customer a free analytics portal”

False. The DIP moves market messages between authorised participants. Customer-facing data access remains a supplier or commercial-service matter.

Potential benefits for businesses

Better consumption insight

Actual interval data can reveal waste that monthly totals hide, including overnight base load, simultaneous equipment start-up and weekend operation.

More accurate procurement

A supplier can price the real shape rather than relying on a broad profile. The business can also compare quotes using the same data.

Greater value from flexibility

Batteries, managed charging, thermal storage and controllable processes can respond to time-varying prices or flexibility events.

Improved solar and export analysis

Half-hourly import and export records show when generation is used on site and when it is sent to the grid.

System-wide efficiency

Ofgem’s MHHS decision and full business case estimated net benefits of £1.559 billion to £4.509 billion for GB consumers over 2021 to 2045.

This is a whole-market appraisal, not a promised saving on each business’s invoice. Implementation cost, supplier competition and product design determine how much reaches a particular customer.

Risks and limitations

Poor data quality

More granular systems create more values to validate. A wrong multiplier or systematic communications fault can affect thousands of intervals.

Peak exposure

A tariff linked closely to expensive periods can penalise a business that cannot change its operating hours.

Contract overlap

Legacy and replacement metering charges can overlap if notices, appointments and commercial terms are not coordinated.

Estimated data mistaken for actual data

Settlement-shaped values for a traditional meter can look like a complete half-hourly dataset. The business should check the quality indicator and source.

Technology cost

Controls, batteries and software have capital, maintenance and cybersecurity costs. A theoretical price spread does not establish a positive return.

Operational disruption

Meter exchanges can require access, isolation or an outage. Complex sites need planning and correct technical records.

Privacy and governance

Interval data can be commercially sensitive. Access rights, retention, user permissions and data sharing should be documented.

Overstated supplier claims

“MHHS-ready”, “dynamic” and “smart” are not complete commercial specifications. Ask for the actual role, tariff formula, time bands, data source and charges.

Frequently asked questions

Final MHHS checklist for businesses

Before or during migration, confirm:

1. Every electricity MPAN is included in a current site register.
2. Import and export MPANs are listed separately.
3. Meter serial numbers match the installed equipment.
4. Meter type and connection type are known.
5. Current supplier and contract dates are recorded.
6. MOP, DC/DA, communications and portal contracts have been identified.
7. Notice and renewal deadlines have been checked.
8. The supplier has confirmed the MPAN’s migration status and market segment.
9. The intended Metering Service is correctly appointed.
10. The intended Data Service is correctly appointed.
11. Direct-contract and active-appointment records agree.
12. Legacy and MHHS charge effective dates do not create an unexplained overlap.
13. At least 12 months of interval data has been obtained where available.
14. Actual and estimated values can be distinguished.
15. Time zone and daylight-saving treatment are understood.
16. Maximum demand, base load and peak-period consumption have been calculated.
17. Flexible loads have been identified without compromising operations or safety.
18. Time-of-use quotations have been modelled against the full data set.
19. Standing, capacity, network, metering, CCL and VAT costs have been added.
20. The first post-migration bills will receive enhanced checking.
21. Missing data, abnormal peaks and appointment failures have named owners.

Final verdict

MHHS changes the settlement foundation of the Great Britain electricity market. It moves every migrated MPAN into a half-hourly model, using actual smart or advanced-meter data where available and new load-shaping methods where it is not.

The programme is already live. Migration began in October 2025, reached 50% of industry MPANs by early August 2026 and is scheduled to complete on 7 May 2027. The settlement timetable is then being compressed through staged changes associated with M16.

For most small businesses, migration should be supplier-led and largely invisible. It does not automatically require a new meter, a new contract or a different unit rate.

The strategic effect emerges at renewal. Suppliers can price actual load shape more directly, while businesses can use interval data to compare tariffs, control peaks, manage EV charging, improve solar self-consumption and evaluate batteries or flexibility services.

The commercial result is not automatically positive. A flexible site may save money; a peak-heavy site can pay more. A traditional meter may still rely on calculated values. An uncoordinated MOP or data contract can create duplicate cost.

The strongest response is therefore practical: identify every MPAN, verify its meter and migration status, secure access to reliable data, map every metering contract and model future tariffs against the business’s real operating profile.