Boiler Upgrade Scheme (BUS)

Document research last revised 2026-08-14.

Grant Name

Boiler Upgrade Scheme (BUS)

Scheme Administrator

Ofgem. Ofgem assesses applications, issues vouchers, carries out audit and compliance checks, and pays grants to installers following successful redemption. (Ofgem)

Opportunity Type

Low-carbon heating / clean heat / energy efficiency infrastructure

Primary Area

Heat pumps, low-carbon heating and building decarbonisation. (GOV.UK)

2026/27 Scheme Allocation

Ofgem's current guidance lists an indicative £400 million allocation for 2026/27. Some funding across 2026–2030 has been set aside for potential innovation activity and therefore may not all be directly available for BUS vouchers. (Ofgem)

Current Remaining Budget

£233.817 million remained for the 2026/27 scheme year as at 31 July 2026, according to Ofgem's latest monthly update published on 11 August 2026. (Ofgem)

Standard Air-to-Water Heat Pump Grant

£7,500. (GOV.UK)

Standard Ground-Source Heat Pump Grant

£7,500, including eligible water-source heat pumps and shared-ground-loop arrangements. (GOV.UK)

Off-Gas-Grid Heat Pump Grant

£9,000 for an air-to-water or ground-source heat pump where the property is off the gas grid and is replacing an oil or LPG heating system. Available for qualifying applications properly made from 21 July 2026 until 31 March 2027. Self-build properties are excluded from this uplift. (Ofgem)

Air-to-Air Heat Pump Grant

£2,500. Air-to-air heat pumps are eligible for residential properties only. (GOV.UK)

Biomass Boiler Grant

£5,000. Biomass boilers are subject to additional rural, off-gas-grid and emissions requirements. (GOV.UK)

Number of Grants

Generally one BUS grant per property. (GOV.UK)

Scheme End / Application Deadline

The scheme has been extended to 2030. The final date on which Ofgem can issue BUS vouchers is 31 December 2029. Ofgem states that further details about applications close to this date will be provided nearer the time. (Ofgem)

Important Deadline Correction

The linked Find a Grant page still shows 31 December 2027, but current Ofgem V5.1 guidance confirms that BUS has been extended to 2030 and that vouchers may be issued until 31 December 2029. For publication, the current Ofgem guidance should be used. (Find a Grant)

Eligible Residential Properties

Examples include owner-occupied homes, privately rented properties, second homes, holiday homes and park homes, provided the property and installation meet the scheme requirements. (Ofgem)

Eligible Non-Residential Properties

Eligible non-residential buildings can include properties such as churches, community centres and office spaces, subject to scheme requirements. Air-to-air heat pumps are restricted to residential properties. (Ofgem)

Eligible Self-Build Properties

Certain genuine self-build properties can qualify for heat pumps, provided they meet the BUS self-build criteria. Self-build properties are not eligible for biomass-boiler grants or the £9,000 off-gas-grid uplift. (GOV.UK)

Ineligible Properties / Applicants

Social housing, including qualifying shared-ownership social housing; most developer-built new-build properties; and properties that have already received public funding for a low-carbon heating system are generally not eligible. (Ofgem)

Social Housing

Social housing is not eligible. This includes homes owned or managed by councils, registered social landlords/housing associations and relevant shared-ownership schemes. Former social housing that has subsequently become privately owned, for example through Right to Buy, may qualify. (Ofgem)

Existing Heating System Requirement

For retrofit properties, the system being replaced must generally be a fossil-fuel system such as gas, oil, LPG or coal, or an eligible electric heating system such as storage heaters, panel heaters or an electric boiler. (Ofgem)

Existing Low-Carbon Heating

A property is not eligible where the previous space-heating system already includes a heat pump. BUS cannot normally be used simply to replace an existing low-carbon heating system. (Ofgem)

Fossil Fuel Replacement Requirement

Existing fossil-fuel heating must be fully replaced. A fossil-fuel heating system cannot normally remain alongside the BUS-funded heat pump. (Ofgem)

Supplementary Heating

From 28 April 2026, BUS-funded heat pumps may be installed alongside eligible non-fossil-fuel supplementary heating appliances, such as direct electric heating, storage heaters, heat batteries or certain other heat pumps, provided scheme requirements are met. (Ofgem)

EPC Requirement

A valid Energy Performance Certificate is no longer mandatory. This requirement was removed from 28 April 2026. Where a valid EPC exists, its reference number must still be supplied. (Ofgem)

Evidence Where No EPC Exists

Where there is no valid EPC, the installer must provide alternative evidence of eligibility. This can include a recent utility bill or fuel receipt, photographs of the existing heating system and details of an expired EPC where available. (Ofgem)

Utility Bill / Fuel Evidence

Where used instead of an EPC, a utility bill should generally be dated within the previous three months. For fuels bought less frequently in bulk, the most recent available fuel receipt may be used. (Ofgem)

Installer Requirement

The installation must be carried out and commissioned by an installer certified under the Microgeneration Certification Scheme (MCS) for the relevant technology. (Ofgem)

Heat Pump Capacity Limits

Maximum capacity is generally 45 kWth for an individual heat-pump system, 70 kWth for an eligible multi-heat-pump system, and 300 kWth total for a shared ground-loop system, with each connected heat pump not exceeding 45 kWth. (Ofgem)

Heat Pump Efficiency Requirement

Eligible air-to-water and ground-source heat pumps must achieve an in-situ seasonal coefficient of performance (SCOP) of at least 2.8. (Ofgem)

Biomass Property Requirement

Biomass boilers must be installed at properties that are off the gas grid and in a rural area. For BUS purposes, rural areas are locations outside settlements with populations exceeding 10,000 people. (Ofgem)

Biomass Technical Requirements

The biomass boiler must generally be no more than 45 kWth, provide the property's full space and hot-water heating demand, and meet BUS emissions requirements. Biomass stoves are not eligible. (Ofgem)

Biomass Emissions Requirement

An eligible biomass boiler must have an emissions certificate demonstrating compliance with BUS air-quality limits. (Ofgem)

Public Funding Restrictions

BUS cannot normally be combined with other public funding for the same low-carbon heating installation, and a property that has previously received public funding for another low-carbon heating system at the same address may be ineligible. Separate funding for unrelated energy-efficiency measures such as insulation can still be permitted. (Ofgem)

System Ownership Requirement

The property owner must become the legal owner of the new heat pump or biomass boiler after installation. Finance arrangements where a third party retains ownership of the heating system are not eligible. (Ofgem)

Ineligible / Restricted Costs

The current guidance does not provide a simple itemised “ineligible costs” list. BUS cannot fund an ineligible heating technology/configuration or duplicate public funding for the same installation. Funding is also not available simply to replace an existing low-carbon heating system. (Ofgem)

Applicant Contribution

BUS provides a fixed grant rather than funding the full project cost. The property owner pays the remaining installation cost after the applicable BUS grant has been deducted. (GOV.UK)

Application Method

Installer-led. The property owner does not submit the BUS application themselves. An MCS-certified installer applies for a voucher on their behalf. (Ofgem)

Property Owner Consent

After the installer submits the application, Ofgem contacts the property owner directly to confirm that they consent to the installer applying on their behalf and to verify their identity. (Ofgem)

Consent Deadline

The property owner normally has 14 days to provide online consent. For the assisted-digital telephone/postal route, Ofgem allows 28 days. (Ofgem)

Retrospective Applications

A BUS application can in some circumstances be made after the system has been commissioned, but it must be properly made within 120 days of the commissioning date shown on the MCS certificate. (Ofgem)

Important 120-Day Clarification

Your original note stating that every application must be made within 120 days of commissioning is too broad. The 120-day rule applies particularly to retrospective applications. Where a voucher is issued before installation, the separate three- or six-month voucher validity period applies. (Ofgem)

Grant Payment

The full grant value must be deducted from the property owner's quote before payment is made, and it must also appear on the final invoice. Ofgem pays the grant directly to the installer after successful voucher redemption. (Ofgem)

Monitoring and Audit

Ofgem can carry out application and installation audit/compliance checks, including requests for evidence and potential visits to the property. MCS may also contact property owners as part of quality-assurance checks. (Ofgem)

Record Keeping

Installers must retain information relied upon for BUS voucher and redemption applications for six years from the date the applications were made. (Ofgem)

Objectives

To increase deployment of low-carbon heating, support the transition away from fossil-fuel heating and help scale up the heat-pump market. (Find a Grant)

Latest Scheme Statistics

Latest Ofgem operational data, covering 23 May 2022 to 31 July 2026, records 143,650 voucher applications received, 96,951 vouchers issued, 90,115 vouchers redeemed, and £635.3775 million in grants paid. (Ofgem)

Total Value of Vouchers Issued

£687.141 million as at 31 July 2026. (Ofgem)

Latest Statistics Publication Date

Ofgem's latest BUS monthly figures were updated 11 August 2026 and cover activity to 31 July 2026. (Ofgem)

Contact Email – General Enquiries

BUS.Enquiry@ofgem.gov.uk (Ofgem)

Application / Scheme Website

Ofgem Boiler Upgrade Scheme; applications are submitted by MCS-certified installers through the BUS installer portal. (GOV.UK)

VAT Note

Ofgem currently states that installations of qualifying energy-saving materials, including heat pumps and biomass boilers, benefit from 0% VAT until 31 March 2027. (Ofgem)

Important Notes

Major 2026 changes: valid EPC no longer mandatory from 28 April 2026; air-to-air heat pumps are now eligible for a £2,500 grant; qualifying off-gas-grid oil/LPG properties can receive £9,000 for air-to-water or ground-source heat pumps from 21 July 2026 to 31 March 2027; and BUS has been extended to 2030. (Ofgem)

Heat Battery Note

The Warm Homes Plan announced an intention to introduce standalone support for heat batteries, but the current Ofgem V5.1 grant categories and current GOV.UK “What you can get” page do not yet list a standalone heat-battery BUS grant. Heat batteries can currently appear as eligible supplementary heating alongside a BUS-funded heat pump in certain configurations. I would therefore not publish a standalone heat-battery grant amount yet. (GOV.UK)

Last Verified

14 August 2026

Application deadline in source document

The scheme has been extended to 2030. The final date on which Ofgem can issue BUS vouchers is 31 December 2029. Ofgem states that further details about applications close to this date will be provided nearer the time. (Ofgem)

Official source

Read the funding authority guidance