Boiler Upgrade Scheme Calculator

What this Boiler Upgrade Scheme calculator does

The Boiler Upgrade Scheme (BUS) is the main government grant for replacing fossil-fuel heating with a low-carbon heat pump or biomass boiler in England and Wales. This calculator shows you exactly what you will pay after the grant is applied, because the money is taken off your installer's quote as an upfront discount rather than paid back to you later. Enter the type of system you want, whether your home is on or off the mains gas grid, the heating you are replacing and your installer's quote, and the tool returns your grant value, your net out-of-pocket cost and the effective percentage the grant covers.

It is built for homeowners, landlords and small businesses comparing real quotes before committing. Crucially, it reflects the rules from 21 July 2026, when off-gas-grid homes replacing an oil or LPG boiler with an air source or ground source heat pump can claim a higher £9,000 grant instead of the standard £7,500. Most older calculators and installer pages still show only the flat £7,500 figure, so this tool helps you avoid under-estimating your saving.

How it works

The grant amount depends on the technology, your gas-grid status and what you are replacing. The verified 2026 grant levels are:

• Air source heat pump (air-to-water): £7,500 — rising to £9,000 for off-gas-grid homes replacing oil or LPG from 21 July 2026.
• Ground source heat pump: £7,500 — rising to £9,000 for off-gas-grid homes replacing oil or LPG from 21 July 2026.
• Air-to-air heat pump: £2,500 (in all cases).
• Biomass boiler: £5,000 — available for off-gas-grid properties only.

Your net cost = installation quote − grant. Installation of heat pumps also carries 0% VAT until 31 March 2027, which your installer applies to the quote. To qualify you must be replacing a fossil-fuel or electric system (not an existing heat pump), the property must be in England or Wales, and you need a valid Energy Performance Certificate (EPC) with no outstanding recommendations for loft or cavity wall insulation. Your MCS-certified installer applies for the grant on your behalf.

Worked example

Sarah lives in a rural cottage that is off the gas grid and currently heated by an oil boiler. She gets a quote of £13,000 to install an air source heat pump, with work scheduled for August 2026 (on or after 21 July 2026).

• Because she is off-grid, replacing oil and installing after 21 July 2026, her grant is £9,000 (not the standard £7,500).
• Net cost = £13,000 − £9,000 = £4,000.
• The grant covers 69.2% of her installation cost, and the quote already includes 0% VAT.

If the same job were done before 21 July 2026, or in an on-gas-grid home, the grant would be £7,500 and Sarah would pay £5,500.

Frequently asked questions

Is the Boiler Upgrade Scheme grant paid to me or my installer?

It is paid directly to your MCS-certified installer, who takes it off your quote as an upfront discount. You never handle the grant money yourself, so you only ever pay the net amount shown by this calculator.

Who can get the higher £9,000 grant?

From 21 July 2026, properties that are off the gas grid and are replacing an oil or LPG heating system with an air source or ground source heat pump qualify for £9,000 instead of £7,500. On-gas-grid homes and air-to-air or biomass systems are not eligible for the uplift.

Do I need an EPC to qualify?

Yes. You need a valid Energy Performance Certificate, and it must have no outstanding recommendations for loft or cavity wall insulation. If it does, you usually have to install that insulation before the heat pump grant can be claimed.

Can I get a grant to replace an existing heat pump?

No. The scheme only supports replacing fossil-fuel systems (gas, oil, LPG or solid fuel) or electric heating. You cannot use it to replace or upgrade a heat pump you already have.

Source: figures verified against GOV.UK – Apply for the Boiler Upgrade Scheme and the official notice of approved grant categories and values. Always confirm current rules with your installer before signing a contract.