Why is John Healey facing a benefits spending Budget headache?

John Healey is under pressure because the UK's welfare bill has risen to around £1 billion a day, a level of spending that's become a major sticking point as he prepares his Budget [1, 2]. That scale of outlay is squeezing the Treasury's finances and pushing officials to look for savings, with speculation growing that tax rises may be needed to help balance the books [1, 2].