How the Boiler Upgrade Scheme Application Works

The Boiler Upgrade Scheme (BUS) pays an upfront grant towards the cost of replacing a fossil fuel or electric heating system with a heat pump or biomass boiler. The application is installer-led: your installer, who must be certified by the Microgeneration Certification Scheme (MCS), applies to Ofgem for a voucher on your behalf, and redeems it once the installation is commissioned¹. You cannot apply yourself³.

The grant never arrives as a cheque. It is deducted from the price you pay: the installer takes the full grant value off the quote before you pay anything, then claims the money back from Ofgem³. The standard grant is £7,500, rising to £9,000 for eligible off-gas grid homes from 21 July 2026, with £5,000 for biomass boilers³. The scheme covers England and Wales only, and it runs until 30 December 2029¹.

How the programme works and who administers it

The Boiler Upgrade Scheme is a government scheme providing upfront grants to help reduce the cost of installing heat pumps and biomass boilers in homes and non-domestic buildings². It launched on 23 May 2022, with vouchers issued from that date for eligible technologies installed from 1 April 2022⁸. The scheme supports the decarbonisation of homes and small and medium non-domestic buildings in England and Wales¹, and as of 28 April 2026 it has been extended to 2030³. The published closing date for applications is 30 December 2029, 11:59pm¹.

Ofgem administers the scheme on behalf of the Gas and Electricity Markets Authority¹⁰. In practice that means Ofgem receives the voucher applications installers submit, checks eligibility, issues the vouchers, processes redemption applications after commissioning, pays the grant to installers, and audits installations. Ofgem is also required to publish quarterly and annual reports on its website, and aims to publish monthly operational updates³.

The scheme exists because heat pumps cost more to install than the gas boilers they replace, and the grant is designed to close that gap at the point of purchase rather than through ongoing payments. It is a capital grant, not a tariff: once the installation is commissioned, the voucher redeemed and the grant paid, there is no continuing relationship with the scheme, unlike the closed Domestic Renewable Heat Incentive, which paid out over seven years.

Funding amounts: £7,500, £9,000, £5,000 and £2,500

The standard grant is £7,500 off the cost and installation of an air source heat pump¹. The grant values are set out in a notice of approved grant categories and values, made under Regulation 13 of the Boiler Upgrade Scheme (England and Wales) Regulations 2022 and approved by the Secretary of State⁵.

From 21 July 2026, eligible off-gas grid properties can apply for an uplifted grant of £9,000 for an air-to-water or ground source heat pump, and this uplifted value is in place until 31 March 2027³. To qualify for the £9,000, the property must not be fuelled by mains gas, and the heating system being replaced must be fuelled by either oil or liquefied petroleum gas (LPG)⁶. Properties that do not qualify for the uplift may still be eligible for the standard £7,500³.

Biomass boilers attract £5,000 off the cost and installation², and the biomass voucher validity period is 3 months³. The grant categories also include a £2,500 value in the approved categories notice⁵; this is the lower category in the approved list, and the headline figures most households will encounter are the £7,500, £9,000 and £5,000 values.

Only one voucher can be redeemed per property, and you can get one grant per property³. A property is not eligible if a previous BUS grant has already been received for installing a heat pump or biomass boiler at the same address³.

Eligibility: your home, existing heating and chosen measure

Only properties located in England and Wales are eligible for BUS funding³. Social housing is excluded, and this includes shared ownership properties³. New build properties which the developer is still building are not eligible; if you move into a finished new build with a fossil fuel boiler, you may still be able to get a grant for a heat pump under the scheme¹². Self-build properties are eligible only for heat pumps, and a self-build means a property built mainly using the labour or resources of the first owner³.

For retrofit installations, the previous heating system being replaced must have been either a fossil fuel based system (such as gas, oil or LPG) or an electric heating system that does not include a heat pump³. The BUS-funded system must fully replace the existing fossil fuel or electric heating system, except where supplementary heating appliances are permitted: from 28 April 2026, BUS heat pumps can be installed alongside supplementary heating appliances provided these are not fossil fuel based³. The main heat-generating unit must always be new¹⁰.

The eligible technologies are air-to-water heat pumps, air-to-air heat pumps, ground source heat pumps (including water source heat pumps and shared ground loops), and biomass boilers³. Air-to-air heat pumps are eligible only for residential properties³. Capacity limits apply: 45 kWth for an individual heat pump system, 70 kWth for a multi heat pump system, and 300 kWth total for shared ground loop systems, with each connected heat pump not exceeding 45 kWth³. Air-to-water and ground source heat pumps must achieve an in situ seasonal coefficient of performance (SCOP) of at least 2.8³. Biomass boilers are limited to 45 kWth, may only be installed in properties in rural areas, and must have an emissions certificate showing particulate matter did not exceed 30g/GJ and NOx did not exceed 150g/GJ net heat input³.

The EPC position changed on 28 April 2026: properties are no longer required to have a valid EPC to apply for BUS³. Earlier guidance required a valid EPC no more than 10 years old¹⁰, and the current scheme pages still describe the EPC check in the eligibility route¹, so the date of the application matters here. Full eligibility detail is on our Boiler Upgrade Scheme eligibility page.

From voucher request to redemption: the two steps

The BUS grant application is a two-stage process⁷. In stage 1, the installer submits a voucher application, and Ofgem checks whether the pre-installation eligibility criteria are met. If the application is successful, Ofgem issues the voucher¹⁴. In stage 2, following commissioning of the installation, the installer submits a voucher redemption application. Once Ofgem has established that the remaining eligibility requirements have been met, the grant payment is made to the installer¹⁴.

Your part in stage 1 is consent and identity verification. A voucher application is only considered "properly made" once Ofgem has all the necessary information to assess eligibility, and the property owner has provided consent and identity verification¹⁰. This is the boiler upgrade scheme consent step: without your verified consent, the application does not enter the queue. Queue position is based on when the voucher application is deemed properly made¹⁰, so delays in providing consent can cost you your place.

The installer must be certified by the Microgeneration Certification Scheme (MCS), a nationally recognised certification scheme for microgeneration installation companies and products¹. All BUS installations must be MCS certified¹⁵, and all heating systems installed under the scheme must meet the relevant MCS standards approved and published by the Secretary of State³. If you are weighing up installers, our page on MCS installer requirements for grants covers what certification means.

A discount at the point of sale, not cash paid to you

The grant is applied upfront as a discount to the cost of your installation. You do not receive the grant directly: it is paid to your installer⁴. Installers must deduct the full BUS grant value from the quote before any payment is made by the property owner³. This is the single most important thing to understand about the scheme's mechanics: the £7,500 never passes through your bank account.

In practice, the sequence is this. The installer quotes for the work, deducts the grant from that quote, and you pay the reduced price. The installer then submits the redemption application after commissioning and Ofgem pays the grant to the installer once the remaining eligibility requirements are met¹⁴. If payment has not been received ten working days after notification of a successful voucher redemption application, installers are told to contact Ofgem¹⁰; that is the installer's chase, not yours.

This structure protects the scheme against grant money being claimed for work that never happens, but it also means the discount depends on the installer applying the rules correctly. The quote you sign should show the grant deduction explicitly. If an installer asks you to pay the full price and promises to refund the grant later, that is not how the scheme is designed to work, since the full grant value must be deducted before any payment is made by the property owner³.

How long vouchers last, the 120-day limit and fresh applications

Once issued, a voucher is valid for a fixed period: within 3 months for air-to-water heat pumps, air-to-air heat pumps and biomass boilers, and within 6 months for ground source heat pumps⁶. Validity periods cannot be extended under any circumstances¹⁰.

Alongside voucher validity sits the 120-day commissioning rule. Your installer must commission and install the heat pump within 120 days of applying for the grant, or it will not be eligible¹². The eligible heating system must be commissioned no more than 120 days prior to the voucher application being properly made⁶, and the redemption application must be properly made within 120 days of the commissioning date³. The 120-day limit after commissioning for submitting a redemption application was introduced from 8 May 2024¹⁷.

The 120-day rule also works retrospectively: installers may apply for a BUS voucher after the installation has been commissioned, provided the application is properly made within 120 days of commissioning⁶. So a household that has just had a heat pump fitted is not automatically too late, but the window is short and absolute.

If a voucher expires before the work is complete, a new application may be submitted¹⁶. For re-applications, Ofgem may grant an extension to the 120-day commissioning rule where the length of time taken to reach certain administrative decisions results, or is likely to result, in the 120-day period being exceeded¹⁰. That extension is narrow: it covers Ofgem's own administrative delays, not a slow installer or a supply problem. Our page on voucher redemption deadlines goes deeper on this.

Funding pots, three-monthly limits and waiting lists

Vouchers are issued on a first come, first served basis, to applicants who meet the eligibility requirements, until the budget cap for the financial year is reached¹⁵. Queue position is based on when the voucher application is deemed properly made¹⁰, which is why completing your consent and identity verification promptly matters.

The scheme had an initial budget of £150m per financial year for 2022 to 2025³. Unspent budget is not carried over to the next scheme year⁷, so a quiet quarter does not create a bigger pot for the next one. Quarterly voucher caps operate from 1 April, 1 July, 1 October and 1 January¹⁰.

Demand has risen sharply since the grant increase. There were 11,256 applications to the scheme between January and March 2025, up 73% from the first quarter of 2024¹⁸, and average monthly applications between November and April were up 49% following the increase in the grant¹⁹. The official statistics report the number of voucher applications and redemptions, as well as the costs of installation¹⁵, and Ofgem's quarterly reports track the remaining budget³. Quarterly reports are published by 31 August (Q1), 30 November (Q2), 28 February (Q3) and 31 May (Q4), and annual reports are published on 31 July each year³.

For a household, the practical implication is timing. A surge in applications can bring a quarter's cap closer, and because unspent budget does not carry over, there is no cushion between quarters. If you are applying near the end of a quarter, the voucher you are issued draws on that quarter's allocation; the scheme's reporting periods run 1 February to 30 April, 1 May to 31 July, 1 August to 31 October, and 1 November to 31 January¹³.

Where ECO4 ends and this support begins

The Boiler Upgrade Scheme sits alongside other funding routes, and the boundaries matter. You cannot get a grant for a hybrid heat pump system, for example a combination of a gas boiler and an air source heat pump¹¹, and only one voucher can be redeemed per property³.

On ECO4, the Energy Company Obligation scheme that funds heating and insulation through energy suppliers, the guidance addresses blended funding with the Boiler Upgrade Scheme directly²⁰. That means BUS and ECO4 are not automatically mutually exclusive, but blending is governed by the ECO4 rules rather than the BUS rules, and the position depends on the measures and obligations involved. Our comparison pages on Boiler Upgrade Scheme vs ECO4 and BUS or ECO4 for a heat pump set out the differences in detail.

Two closed schemes are sometimes confused with BUS. The Green Homes Grant voucher scheme closed without most of its vouchers being used, and the Home Upgrade Grant was the route for off-gas homes; neither can be applied for now. The current off-gas grid uplift within BUS itself, £9,000 from 21 July 2026, is the live route for oil and LPG homes³.

Checks, rules and how to appeal

Ofgem can conduct site or desk audits at any point after a BUS application has been made, including after the grant has been paid⁶. Audits apply to installers and installations, and installers are required to keep all documentation relied upon in voucher applications and voucher redemption applications for six years from the date the application was properly made³.

The evidence Ofgem may ask for is broad: valid ID, proof of address, proof of property ownership, MCS certificate copies, EPCs and EPC site notes, utility bills or fuel delivery receipts, photos of the previous and installed heating systems, purchase receipts or quotes, total building heat loss calculations, and an emissions certificate for a biomass boiler²¹. As a householder, keeping your own copies of the quote, invoice, MCS certificate and evidence of the old system is sensible for the same six-year horizon.

Where non-compliance with the BUS regulations has occurred, the compliance actions available to Ofgem include withholding payments, revoking vouchers, offsetting payments due, or seeking repayment¹⁶. If Ofgem revokes a voucher, it will notify the installer within 14 days of the decision²². Installers can request a review of certain decisions, including a decision to revoke a voucher, and the request must be received within 28 days of the date of the notice of the decision²².

Complaints are split by subject. Complaints about Ofgem's administration of the scheme, or the handling of an application, go to feedback@ofgem.gov.uk³. Complaints about the scheme's underlying policy, including the eligibility criteria, go to the Department at boilerupgradescheme@energysecurity.gov.uk³. Suspected fraud or misuse can be reported to counterfraud@ofgem.gov.uk⁴. General enquiries go to BUS.enquiry@ofgem.gov.uk or by phone on 0330 053 2006³. Changes to the scheme itself are introduced via scheme regulations when parliamentary time allows²³.

What the funding will and will not achieve for self-sufficiency

A BUS-funded heat pump removes the household's dependence on gas, oil or LPG as a fuel: the heating no longer tracks fossil fuel prices or deliveries. For off-gas grid homes on oil or LPG, the £9,000 uplift is aimed squarely at that shift³. The grant also removes the running-cost exposure of old electric heating for homes replacing it.

What remains is real. A heat pump still draws electricity from the grid, so the household remains exposed to electricity prices and to the supplier relationship; the scheme funds the appliance, not the energy it runs on. The household also depends on the installer for the application itself, since the scheme is installer-led and you cannot apply yourself⁴, and on the installer's honesty in applying the upfront discount correctly³. The manufacturer's warranty, the MCS certification and the scheme's audit regime carry the long-term assurance, not the grant.

The scheme's own horizon is bounded: applications close on 30 December 2029¹, the off-gas grid uplift ends on 31 March 2027³, and the budget is capped each financial year with no carry-over of unspent funds⁷. A household planning a heat pump on BUS terms is working against those clocks, not an open-ended entitlement. For the wider picture of how grants fit into a self-sustaining home, see grants and energy independence, and for the full landscape of current support, our home energy grants guide.