The Boiler Upgrade Scheme pays £7,500 toward an air source or ground source heat pump in England and Wales, or £5,000 toward a biomass boiler in eligible rural off-gas homes, and the homeowner never touches the application: an MCS-certified installer files on their behalf and discounts the grant from the invoice. That single procedural fact is where most BUS applications stall. The catch is that the EPC must be no older than ten years and, until May 2024, had to carry no outstanding insulation recommendations at all.
Last reviewed: May 2026
TL;DR
- BUS grant is £7,500 for ASHP or GSHP, £5,000 for biomass (rural off-gas only), uplifted from £5,000 to £7,500 in October 2023 under DESNZ.
- The MCS-certified installer applies through Ofgem's portal on behalf of the homeowner: the homeowner does not file.
- EPC must be valid (issued within ten years) with no outstanding insulation recommendations, though cavity wall and loft were exempted from May 2024.
- England and Wales only: Scotland uses Home Energy Scotland loans, Northern Ireland routes via separate domestic renewable schemes.
- BUS is extended under the Warm Homes Plan to March 2028 per the Spring 2024 DESNZ announcement.
What the BUS grant actually is
The Boiler Upgrade Scheme is a capital grant funded by the Department for Energy Security and Net Zero (DESNZ) and administered by Ofgem. It is not a loan, not a tax credit, and not refundable to the homeowner directly. The grant value is paid to the installer once the heat pump is commissioned and the MCS certificate has been issued.
Three grant tiers exist under the scheme rules:
- £7,500 for an air source heat pump (ASHP).
- £7,500 for a ground source or water source heat pump (GSHP/WSHP).
- £5,000 for a biomass boiler, restricted to rural properties that are off the gas grid and that meet the emissions limits in MCS 008.
The grant was uplifted from £5,000 (ASHP) and £6,000 (GSHP) to a flat £7,500 with effect from 23 October 2023, the largest single step change in domestic heat pump support since the Renewable Heat Incentive closed in March 2022. DESNZ published quarterly BUS statistics showing application volumes more than doubled in the six months after the uplift compared with the six months before.
Who is eligible and what gets disqualified
Eligibility for the Boiler Upgrade Scheme rests on five gates. Miss any one and the application is rejected at the Ofgem stage.
Property location. The property must be in England or Wales. Scotland uses the Home Energy Scotland grant and interest-free loan administered by the Energy Saving Trust on behalf of the Scottish Government. Northern Ireland has historically used the Northern Ireland Renewables Obligation legacy structure with separate Department for the Economy schemes; BUS does not extend to Northern Ireland. Property type. The scheme covers domestic homes and small non-domestic buildings up to 45 kW peak heat output. Self-build properties built by the owner are eligible. New-build homes constructed by a developer are excluded.
EPC validity. A valid Energy Performance Certificate dated within the last ten years must be on the EPC register at the point of application. The EPC is checked automatically against the address.
Insulation status. Until May 2024 the EPC had to show no outstanding recommendations for cavity wall insulation or loft insulation. That requirement was relaxed in the May 2024 update, removing those two specific items as blockers, on the basis that older EPC assessor methodology had been producing false positives for properties that were in fact already insulated.
Heating being replaced. The grant supports replacement of a fossil-fuel heating system. Direct electric heating (storage heaters, panel heaters) is eligible for replacement, but a like-for-like upgrade between two heat pumps is not.
Step by step: from quote to grant payment
The full application sequence runs through nine practical steps. Skipping any of them tends to surface as a rejection at week five or six, after the homeowner has already signed a deposit.
| Step | Action | Who does it | Typical timing |
|---|---|---|---|
| 1 | Initial home survey and indicative quote | MCS-certified installer | Week 1 |
| 2 | Confirm MCS certification status on the MCS register | Homeowner | Week 1 |
| 3 | EPC check against the register | Installer | Week 1-2 |
| 4 | Detailed heat loss calculation under MIS 3005 | Installer | Week 2-3 |
| 5 | Pre-application voucher request via Ofgem portal | Installer | Week 3 |
| 6 | Homeowner consent confirmation to Ofgem | Homeowner | Week 3-4 |
| 7 | Installation and commissioning | Installer | Week 5-10 |
| 8 | MCS certificate issued, lodged with MCS | Installer/MCS | Week 10-11 |
| 9 | Voucher redemption and grant payment | Ofgem to installer | Week 11-13 |
The homeowner sees the grant as a £7,500 discount on the final invoice. The installer recovers the £7,500 from Ofgem after redemption, which is why installer cashflow is one of the silent quality filters in the heat pump market: a thinly capitalised installer cannot wait 11 weeks on every job, so they push customers into unsuitable installs that they can turn around faster.
The MCS certification thread
Everything in BUS routes through MCS. The installer must be MCS-certified at the company level. The product (the heat pump model) must be on the MCS approved product list. The installation must be lodged on the MCS database under MIS 3005-D, which governs domestic heat pump design and installation, and on MCS 008 if a biomass appliance is in scope. The MCS certificate number is the document Ofgem cross-checks against the voucher claim.
Anyone can check installer status at the MCS register. The catch is that the company can be listed under a different trading name from the consumer-facing brand. On the ground, the safest move is to ask for the MCS certification number and search for it directly, not the brand name.
What an MCS heat loss survey is actually checking
MIS 3005-D requires a room-by-room heat loss calculation before quoting. This is the document Ofgem and MCS auditors look at first if a complaint reaches them. It must specify:
- U-values for walls, roof, floor, windows, doors.
- Air change rate per hour and ventilation strategy.
- Design indoor temperature per room (21°C in living rooms, 18°C in bedrooms is the standard CIBSE convention).
- Design outdoor temperature for the postcode (around -1.7°C in London, -3.5°C in Manchester, lower again in the Highlands).
- Total heat loss in watts per room at design conditions, summed to a system size in kW.
An installer who quotes from floor area alone, or from the kW rating of the gas boiler being replaced, has not met MIS 3005. That quote will not survive an MCS audit. In practice, this is the most common reason BUS-supported installs end up oversized and run inefficiently for the first heating season.
Common reasons applications fail
DESNZ data and MCS audit notes converge on a small set of recurring failure modes.
An EPC older than ten years is the most common single failure. The fix is to commission a new EPC, which costs around £50 to £120 depending on region and survey type, and add ten days to the timeline.
An EPC carrying outstanding recommendations beyond cavity and loft insulation also blocks the grant. Solid wall insulation, underfloor insulation, or hot water cylinder insulation flagged on an EPC must be resolved or the EPC must be re-lodged after the works.
The property being a new-build still attracts confusion. The exclusion targets developer new-builds because they were already supposed to meet Part L thermal performance standards; self-builds are eligible, which is the route some custom-build buyers in the Cotswolds and South Devon have used in 2025 and 2026.
A non-MCS installer is a hard stop. There is no derogation, no grandfathering, no "becoming MCS after the job" workaround.
Regional and devolved differences
England and Wales operate the BUS scheme identically through Ofgem. Wales has additional layers via Nest, the Welsh Government's home energy efficiency programme, which can stack with BUS for eligible households on means-tested benefits.
Scotland runs a different model. Home Energy Scotland, delivered by the Energy Saving Trust, offers a grant up to £7,500 plus an optional interest-free loan up to a further £7,500 for an ASHP (the loan element brings the headline package to £15,000 in capital support for households that take both). The Scottish scheme has historically had a rural uplift of £1,500 for properties off the gas grid in postcodes such as IV, KW, HS, ZE and parts of PA.
Northern Ireland does not have a direct BUS equivalent at the same value level. The Department for the Economy in Northern Ireland and the Northern Ireland Sustainable Energy Programme cover energy efficiency support, but the £7,500 ASHP grant available in England does not currently extend across the Irish Sea. Here is where it breaks for buyers in Belfast and Derry expecting parity: the funding envelope has been a devolved decision since the Renewable Heat Incentive scandal closed that scheme in 2016.
How the Warm Homes Plan changed the trajectory
In Spring 2024 DESNZ announced an extension of BUS funding through to 2028 as part of the Warm Homes Plan, with a budget envelope of around £1.5 billion across the three-year window from April 2025. That announcement is what gave installers the confidence to scale capacity. It also signalled that the £7,500 grant level is treated as politically durable rather than provisional.
Quarterly DESNZ BUS statistics published through 2025 showed a sustained increase in voucher redemption rates, with ASHP installs running at roughly seven times the volume of GSHP installs, reflecting the cost gap between an above-ground unit and a vertical borehole or horizontal collector loop.
What a clean application looks like in practice
A clean BUS application has six artifacts attached or referenced: a valid EPC, an MCS company certification number, a model name on the MCS approved products list, a room-by-room MIS 3005 heat loss calculation, a signed customer consent form, and the installer's Ofgem portal voucher reference. With those six, the path from quote to grant payment is typically inside 13 weeks.
The single biggest determinant of success is the installer. Pick one with cashflow to absorb the 11-week lag and the audit track record to survive an MCS check, and the scheme works as designed.
Frequently asked questions
Can a homeowner apply for the BUS grant directly?
No. Only an MCS-certified installer can apply on the Ofgem portal. The homeowner provides consent and an EPC reference, but the application itself is filed by the installer.
Does the BUS grant cover the full cost of a heat pump?
Rarely. Typical ASHP installs run £8,000 to £14,000 before grant, so the £7,500 covers most of an ASHP but not a GSHP, where install costs commonly run £18,000 to £40,000. The grant narrows the gap rather than closing it.
What happens if the property is in Scotland?
Scotland uses the Home Energy Scotland grant and loan package delivered by the Energy Saving Trust, not BUS. The headline grant value is similar at up to £7,500 for ASHP, with an optional interest-free loan on top.
Is the BUS grant taxable income for the homeowner?
The grant is paid to the installer, not the homeowner, so it does not appear as personal income. HMRC has not treated BUS support as a taxable benefit for the homeowner under current guidance.
How long is an MCS certificate valid?
The MCS certificate for a specific installation does not expire, but installer company certification renews annually. Always check the company status on the MCS register before signing a deposit.
Can the BUS grant be combined with ECO4?
The two schemes target different gaps. ECO4 is supplier-funded and targets low-income and vulnerable households for insulation and heating measures. BUS is the capital grant for the heat pump itself. In limited circumstances they can be sequenced, but they cannot both pay for the same item of work.