Tory chancellor George Osborne forced seven government departments to announce further cuts last week.
He is looking for £11.5 billion cuts for 2015-16.
The Ministry of Justice, the Department for Communities and Local Government and five other ministries have signed up for cuts of 8-10 percent to their budgets.
Iain Duncan Smith says he’d be willing to cut an extra £3 billion to benefits, in an attempt to stop cuts in other departments.
He proposes denying housing benefit to under 25s and child benefit to anyone with the misfortune to be born with two or more siblings.
But Osborne refuses “to let Whitehall off the hook” as he urgently needs the cash.
A recent review estimated that Universal Credit will cost £12.8 billion to set up—nearly six times more than originally billed.