The freedom for Whitehall departments and public service managers to carry over unspent revenue and capital from one year to another is under intensifying pressure from the Treasury as it grapples with dire public finances.

The National Audit Office on Wednesday revealed the Department for Children, Schools and Families had £2.4bn ($3.6bn) of unspent capital in the bank at the end of March, up £500m on last year, while schools held £1.9bn of unspent revenue – £250m up on the year.