The Boiler Upgrade Scheme has a couple of time limits, and they cause a lot of worry, but missing one rarely means losing the grant for good. This page explains the two main timescales, what happens if you run past them, and who is responsible for each, sourced to gov.uk and Ofgem. For the current grant values and scheme status, see our Boiler Upgrade Scheme grant tracker.
The voucher validity period
When a Boiler Upgrade Scheme voucher is issued, you have 3 months to complete and commission the installation, or 6 months for a ground source heat pump. If the voucher expires before the heat pump is commissioned, the grant is not lost permanently: you can re-apply for a new voucher. The voucher is applied for by your MCS-certified installer and the grant is taken off your bill, so coordinate timing with them early.
The 120-day commissioning rule (installer side)
Separately, Ofgem requires that the voucher application is properly made within 120 days of the commissioning date stated on the MCS certificate. This is an installer-facing rule. In very limited circumstances Ofgem may grant an extension where administrative delays push a re-application past the 120-day window. Because this sits with the installer, choose an experienced MCS installer who manages the scheme paperwork routinely.
What to do if a deadline is slipping
- Talk to your installer as soon as you know the work will be late, before any voucher expires.
- If a voucher does expire before commissioning, ask the installer to re-apply for a new one.
- Keep the MCS certificate and commissioning date safe, as the 120-day rule is measured from it.
- Check the current scheme rules on gov.uk and Ofgem before relying on any deadline, as scheme detail changes.
Common questions
How long is a Boiler Upgrade Scheme voucher valid?
A voucher is valid for 3 months from the date it is issued, or 6 months for a ground source heat pump. The installation must be commissioned within that window, according to Ofgem and gov.uk guidance.
What if my voucher expires before the work is done?
You do not lose the grant outright. If the voucher expires before the heat pump is commissioned, you can re-apply for a new Boiler Upgrade Scheme voucher, per Ofgem guidance. Your MCS installer makes the application.
What is the 120-day rule?
It is an installer-facing rule: the voucher application must be properly made within 120 days of the commissioning date on the MCS certificate. Ofgem may grant an extension in very limited circumstances where administrative delays are the cause.
Sources
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This is general information, not mortgage, legal or surveying advice. VettedHome is an independent home information site, not a lender or installer.
Editor, VettedHome
Adam leads VettedHome's editorial coverage of UK home services. He is the founder and managing director of Muswell Rose, the commercial strategy and modern systems business behind a portfolio of UK information sites, and he researches and writes the plain-English guides that help homeowners choose between installers and trades, drawing on the standards set by the relevant bodies for each job, such as Gas Safe Register, NICEIC, MCS, TrustMark and the Property Care Association. He is clear about what to check before any work starts.
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