How Does the Boiler Upgrade Scheme Work? 2026 Guide

These are the current grant categories under the official BUS rules effective from 21 July 2026.

You can receive one BUS grant per property. Hybrid heat pumps that retain a fossil-fuel boiler are not eligible, and the grant cannot be used to replace an existing low-carbon heating system.

The government has extended BUS through the 2029/30 financial year, commonly described as running to 2030. However, individual grant amounts and eligibility rules can still change, so check the current position before signing a contract.

How Does the Boiler Upgrade Scheme Work Step by Step?

1. Find an MCS-Certified Installer

BUS is installer-led. Start by getting quotations from installers certified under the Microgeneration Certification Scheme for the technology you want. Ofgem confirms that eligible BUS installers must hold the relevant MCS certification.

The installer should assess whether your property and proposed system meet the rules.

If you are choosing between technologies, our air source vs ground source heat pump guide explains the practical differences.

2. Agree a Quote With the Grant Already Deducted

Before installation, the quote should show the full BUS grant as an upfront deduction.

For example, if an eligible project costs £12,000 and attracts a £7,500 grant, the remaining customer contribution would be £4,500.

That is only an example, not a typical quotation. Costs vary with system size, emitters, hot-water requirements, electrical work, access and other site-specific factors.

Ofgem requires installers to show the full BUS discount on both the quotation and final invoice. The installer must not collect the grant amount from you and tell you to reclaim it later.

3. The Installer Applies to Ofgem

Once you agree the project, the installer submits the BUS voucher application.

You do not make the main grant application yourself. The confirms that the installer applies on your behalf.

Ofgem then contacts you to confirm that the installer is acting for you and to check relevant eligibility details.

4. Ofgem Checks the Application and Issues the Voucher

Ofgem assesses the information supplied by your installer.

If the application meets the scheme requirements, Ofgem issues a grant voucher to the installer. The voucher is not cash paid to you. Instead, it allows the installer to claim the agreed grant after completing an eligible installation.

5. The Installer Completes and Commissions the System

The installer completes the installation to the relevant technical and MCS standards.

After commissioning, an MCS installation certificate is generated. This forms part of the information used when the installer redeems the BUS voucher.

If you are moving from a conventional boiler to an air-to-water system, it helps to understand how air source heat pumps work before approving the final specification. Radiator sizing, flow temperatures and hot-water arrangements can all affect the work required.

6. The Installer Redeems the Voucher

After commissioning, your installer applies to Ofgem to redeem the voucher.

Ofgem carries out final eligibility checks, including reviewing the MCS installation details. Once redemption is approved, Ofgem pays the grant to the installer.

This is why BUS is best understood as an upfront discount backed by an installer voucher, rather than cashback paid to the homeowner.

7. You Pay the Remaining Balance

You pay the contract price after the BUS discount, plus any separately agreed work outside the quoted project.

Compare quotations on a like-for-like basis. A low customer contribution can still represent poor value if essential radiator, electrical or hot-water work has been excluded.

Who Is Eligible for the Boiler Upgrade Scheme?

BUS applies to qualifying properties in England and Wales.

Eligible owners can include homeowners, landlords, second-home owners and owners of qualifying business properties. GOV.UK specifically confirms that owned rental properties, second homes and business properties can potentially qualify.

For most retrofit projects, the new system must replace an existing fossil-fuel or electric heating system.

Most new-build properties and social housing are excluded. However, qualifying self-build homes can be eligible for heat-pump support.

You also cannot normally receive BUS if public funding has already contributed towards purchasing or installing the same heat pump or biomass boiler. Separate support for other energy-efficiency improvements, such as insulation, does not automatically make you ineligible.

Biomass has tighter rules. The property generally needs to be rural and off the gas grid, while the boiler must meet specific emissions and technical requirements.

Air-to-air BUS support, meanwhile, is limited to residential properties.

Do You Need an EPC for the Boiler Upgrade Scheme in 2026?

A valid Energy Performance Certificate is no longer a standing BUS eligibility requirement for applications properly made from 28 April 2026.

Where a valid EPC exists, the installer should provide its reference number. Where one does not exist, Ofgem allows the installer to submit alternative evidence demonstrating the relevant property and heating-system details.

This removes a potential administrative barrier.

However, energy efficiency still matters in practice. Reducing heat loss can reduce the amount of heat your new system needs to provide and can improve comfort. Ofgem also advises that insulation may improve heat-pump performance and reduce running costs.

What Does the BUS Grant Actually Pay For?

The grant contributes towards the cost and installation of an eligible low-carbon heating system. It does not guarantee that your whole project will be free.

Your remaining cost depends on the total quotation after the grant. A heat-pump project may involve radiators, pipework, hot-water storage, controls, electrical work or groundworks.

For the longer-term picture, our air source heat pump running costs guide explains the factors affecting electricity use.

Our guide to whether air source heat pumps are worth it looks at the wider ownership decision.

How Long Does a BUS Voucher Last?

After Ofgem issues a voucher, an installer generally has three months to complete an air-to-water, air-to-air or biomass installation. Ground source heat-pump vouchers normally remain valid for six months.

If the voucher expires before completion, the installer can reapply. You will need to confirm your consent again.

Some retrospective applications are possible where the system has already been commissioned, provided the application is properly made no more than 120 days after commissioning. However, proceeding before obtaining a voucher carries greater financial risk because the grant has not yet been approved.

What Should You Check Before Agreeing a BUS Quote?

Check that the quotation identifies the technology, total project price, BUS grant as a separate upfront deduction and the amount you must pay.

Confirm what the price includes for radiators, hot water, controls, electrics, groundworks and making good.

Also check that the installer is MCS-certified for the relevant technology and can participate in BUS.

If a company asks you to pay the grant amount and promises that you can claim it personally afterwards, that does not match Ofgem’s standard installer-led process.

Finally, do not choose a system simply because it attracts a grant. BUS reduces capital cost; it does not prove that a particular system is right for your property.