- Eligible projects now have until March 2030 to commission under the Green Gas Support Scheme.
- New stage-one applications still close in March 2028, while support for later-stage projects ends by March 2043.
- Developers gain construction flexibility but must assess the value of a shorter payment period and the conditions attached to existing applications.
Britain’s extended commissioning window for subsidised biomethane projects took effect on 16 October, giving eligible developers two additional years to bring plants into operation while limiting how long later projects can receive support.
The Green Gas Support Scheme amendment regulations move the final commissioning deadline from 31 March 2028 to 31 March 2030. The scheme supports eligible biomethane produced through anaerobic digestion and injected into the gas network in England, Scotland and Wales.
The change implements a previously announced extension rather than establishing a new support programme. Crucially, it does not move the deadline for submitting new stage-one applications beyond March 2028.
Developers also face a financial qualification. The standard support period is 15 years, but payments for projects with a tariff start date after March 2028 cannot extend beyond 31 March 2043. A project starting at the final March 2030 deadline would therefore receive approximately 13 years of support.
That makes the extension valuable for projects facing delays, while preventing developers from treating the additional construction time as financially neutral.
Application dates determine flexibility
The regulations distinguish between groups of applicants. Ofgem can, on request and subject to the relevant conditions, reissue tariff-guarantee notices for applications made from 10 December 2025, allowing a later injection date no later than March 2030.
Applicants from before that date do not receive the same route automatically. Government guidance says those unable to meet their existing commissioning date may choose to withdraw and reapply, but acceptance would depend on the eligibility criteria and conditions applying at that time.
The practical consequence is that developers and lenders need to examine individual tariff guarantees before revising construction schedules. A general extension to the scheme does not establish identical rights for every project already in development.
DESNZ also updated its budget documentation on 16 October, extending published budget caps and inflation forecasts through 2034/35. The application budget limits estimated commitments, while the overall expenditure budget informs the levy used to finance the scheme. These are budget-management arrangements rather than immediate grants to individual plants.
Some administrative changes follow a different timetable. Provisions concerning scheme-year reporting and reconciliation take effect in April 2027, rather than alongside the principal October amendments.
The investment calculation
For projects with credible feedstock arrangements and a viable gas connection, the extension can reduce the risk that construction delays eliminate access to support altogether. It gives developers more room to coordinate equipment delivery, financing and commissioning.
The shorter payment period introduces a counterweight. Delaying operation may preserve eligibility, but it can reduce the supported revenues available to repay debt and recover construction costs. Inflation-linked tariffs do not remove that issue, because an indexed annual payment and an additional year of payments have different financial values.
Developers therefore need to compare the cost of accelerating construction with the value of starting support earlier. That calculation will vary with borrowing costs, capital expenditure and expected operating performance.
The extension also leaves the underlying delivery requirements intact. Plants still need dependable feedstocks, effective operations and compliance with the scheme’s sustainability rules. More time cannot compensate for an uneconomic supply chain or an unworkable connection.
For the UK biomethane sector, the change provides useful certainty about the outer commissioning deadline. Its commercial value will depend on how much of the development pipeline can use that flexibility without sacrificing too much of the revenue period that makes investment possible.
