The Telegraph, citing multiple government sources, reported that the budget was for a 12 month period after March, including next winter.
Finance minister Jeremy Hunt called the current six-month programme "unsustainably expensive" on Wednesday, with his department saying the government will set out a plan next week on how it intends to scale back the subsidies for businesses.
The original programme was predicted to cost 18.4 billion pounds ($21.84 billion) when the government's budget watchdog published forecasts in November.
The finance ministry did not immediately respond to a request for comment on the Telegraph report.
($1 = 0.8424 pounds)
(Reporting by Muvija M; editing by William James)