The Commons expenses watchdog is embroiled in a furious row with MPs after it "named and shamed" dozens who had failed to settle debts.
Ministers Tobias Ellwood, Edward Timpson and Caroline Dinenage were among 26 politicians listed as not paying outstanding sums of up to £500 last year - forcing them to be written off.
The Independent Parliamentary Standards Authority (Ipsa) insisted it asked the individuals numerous times to either justify the expenditure or hand back the money, and warned them that they would be publicly identified.
But while Mr Ellwood and Mr Timpson agreed to stump up following a rebuke from Downing Street, other current and former MPs angrily denied that they had done anything wrong. Some suggested privately that the watchdog should not be humiliating them over "piddling" sums.
The debts written off range from a few pounds to hundreds. Much of the spending was on official credit cards that are automatically paid off by Ipsa before checks on whether they are allowable.
Children's minister Mr Timpson put a £127.50 "public transport" bill on his card - before later ticking a box on a form indicating he did not want to claim the sum as expenses.
Foreign Office minister Mr Ellwood - who recently wrote a letter to the watchdog backing the controversial 10% MP pay rise because he was "watching the pennies" - owed for three claims.
A £5 spend on food and drink was deemed outside the rules by Ipsa, while a £17 train ticket was a duplicate. He said he did not want to claim for a £4.50 parking charge but did not repay the cash.
Chris Skidmore, parliamentary aide to Chancellor George Osborne, spent £125 on a London hotel but the claim was deemed not allowable under the rules.
Equalities minister Ms Dinenage paid a £13.50 constituency office telephone bill on card but it was later deemed ineligible.
Downing Street quickly made clear David Cameron's displeasure with the situation. "The Prime Minister's view is that he expects any ministers who owe money to pay it back," a spokeswoman said.
Ipsa said Mr Ellwood and Mr Timpson had been in touch to say they would settle the bills. Ms Dinenage's office said Ipsa had agreed the spending was valid this afternoon after she provided further information.
Details of each MP's expenses and office costs for 2014-15 have also been published - with spending rising 1.6% to nearly £106 million.
The overall increase in spending between 2013-14 and 2014-15 was the slowest in recent years, and could indicate that many MPs were winding down their activities ahead of the general election.
Staffing costs went up by £2.2m to £82.7m, but spending on flats, hotels, travel and subsistence was down around £150,000 at £11.6m.
The amount laid out on renting and equipping offices was £10.7m.
Politicians had 4,021 staff on the books compared with fewer than 3,000 in 2009-10.
Some 169 MPs employed a family member or business associate in their office in 2014-15 - up two on the previous year.
Spending on enhanced security for individual MPs more than doubled from £33,726 to £77,234 last year. The watchdog said the measures were only authorised on police advice.