David Cameron has accused Gordon Brown of "staying in the Downing Street bunker" rather than voting against the MPs' "John Lewis list" expenses.
MPs have rejected a Tory attempt to stop them spending up to £24,000 a year of taxpayers' money on furnishing their second homes.
The Tory leader pressed Mr Brown to explain why he had not "turned up" for the vote, adding: "When leadership was required, you didn't provide it."
Instead they backed a government move to reimburse "reasonable costs" of up to £2,400.
The PM claimed Mr Cameron ran away from big decisions on issues like terrorism.
Shadow Commons leader Theresa May said this amounted to replacing the "John Lewis list" of household goods they can claim with an "Ikea list".
The exchanges came ahead of a debate in which Labour and the Tories will unveil plans to reform MPs' expenses rules.
Earlier this month MPs voted to keep their £24,000 second home allowances.
The Tories want to scrap most of the items MPs can currently claim for a second home, including furniture and electrical goods.
This would leave the £24,000 allowance covering mortgages or rent, council tax and utility bills.
Reforms
Labour would let the National Audit Office judge what is reasonable expenditure, instead of using the prices John Lewis charges as a measure.
MPs voted against radically reforming their expenses earlier this month.
At question time in the Commons, Mr Cameron told the prime minister: "You had a chance to vote against the John Lewis list and you flunked it - you stayed in the Downing Street bunker.
"Yet again when leadership was required, you couldn't provide any."
Mr Brown has made it clear he was disappointed with the free vote in which many of his own MPs, including 34 members of the government, rejected a proposal to abolish the John Lewis list.
Council tax
The system deems what is reasonable for MPs to spend on furnishing and improving their constituency homes.
The Tories will bring the issue before Parliament again by using an Opposition Day debate to consider MPs' expenses.
Labour has responded by tabling their own amendment. They would allow MPs to spend £2,400 a year furnishing their second homes, but would use the independent National Audit Office as a measure of reasonable expenditure, rather than the John Lewis list.
In a statement, Commons Leader Harriet Harman said the government wanted to change the allowance "so that the reasonable reimbursement of the costs of furniture and other household goods be capped at 10% of the ACA in any one year".
The Conservatives say they have forced the government's hand on the issue as they have instigated Wednesday's debate.
Mr Cameron will also publish the detailed expense claims for the first three months of this year for the overwhelming majority of Conservative MPs, including his entire front bench.
Labour say they are serious about their proposed reforms and will try to rush them on to the statute books before the summer recess.
The John Lewis list system - officially known as the Additional Costs Allowance - allows MPs to spend £24,000 a year on the cost of a second home.
