The Full Business Case for the extension of the Boiler Upgrade Scheme was approved by the Project Investment Committee, now known as InvestCo, in November 2025, according to an accounting officer assessment published by the Department for Energy Security and Net Zero1. The same document states that the case then passed a Treasury Approval Point in January 20261. The scheme has been in delivery since April 20221.
The assessment sets out the scheme's statutory basis and delivery arrangements. The Boiler Upgrade Scheme is established under the Boiler Upgrade Scheme (England and Wales) Regulations 2022 (SI 2022/565), made using powers conferred by sections 100 and 104 of the Energy Act 20081. It is delivered by Ofgem on behalf of DESNZ, which retains responsibility for policy design, funding and overall accountability, while Ofgem handles installer registration, grant processing, compliance and assurance1. The scheme joined the Government Major Projects Portfolio in July 2024 and reports quarterly to the National Infrastructure and Service Transformation Authority1.
The document describes the scheme's purpose in these terms:
"The BUS supports the decarbonisation of domestic heating in England and Wales by providing capital grants to encourage the installation of low‑carbon heating technologies, including heat pumps and biomass boilers as replacements for existing fossil fuel systems."
The assessment records that the scheme has satisfied the four accounting officer standards of regularity, propriety, value for money and feasibility, and that the DESNZ Accounting Officer approved it on 23 April 20261. On feasibility it states that the scheme is "well established operationally, with four years of successful delivery having already taken place"1. It also notes that key risks, including demand uncertainty, supply chain capacity and consumer awareness, are actively managed and kept under review1.
The document does not set out grant amounts, eligibility rules, application deadlines or the length of the extension. Those details have not been reported in this assessment. Households wanting to check whether their home or heating system qualifies can read the guidance on eligibility, including the position for homes with an existing gas boiler and the EPC and insulation requirement. The grant amount and the application process are covered separately, as are the rules for landlords and second homes and social housing.
Why it matters for households
The approval of the Full Business Case is an internal governance step, not a change to the grant itself. Its practical significance is that the extension of the scheme has cleared the approval points that release it to continue, which matters to any household weighing up a heat pump or biomass boiler against the cost of replacing a fossil fuel system. A grant that is confirmed to continue reduces the risk that a household commits to an installation on the basis of support that then closes.
The assessment also confirms the split of responsibilities that households encounter in practice: DESNZ sets policy and funding, while Ofgem runs installer registration, grant processing and compliance1. For a home's energy independence, the scheme's stated aim is to replace existing fossil fuel heating with low carbon systems1, which shifts a household away from a fuel it does not control the price of. The document gives no figures on how many homes the extension is expected to reach, and no costs per installation.
What happens next
The assessment states that the project will continue to provide information through quarterly and annual reporting to the Government Major Projects Portfolio and will be subject to an annual assessment by NISTA1. A summary of the Full Business Case is to be published alongside the assessment1. The document adds that if any of the factors it covers change materially during the project's lifetime, a revised summary will be prepared1. No date has been given for the end of the extension period.