Chancellor George Osborne is to launch an independent review of government spending after the prime minister claimed Gordon Brown had blown huge sums prior to leaving office.
Speaking to the BBC on Sunday, David Cameron claimed Labour ministers had gone on "crazy" spending sprees before losing power.
Among the measures allegedly passed was a bumper £15m bonus deal for senior civil servants.
Mr Cameron also used the interview to rule out a hike in VAT to 20%, saying Capital Gains Tax would be reformed instead.
Talks to axe family credits for those earning more than £50,000 are ongoing, he added.
Mr Osborne's review, to be conducted by the new Office of Budget Responsibility under Sir Alan Budd, comes ahead of an emergency budget scheduled for June and a wide-ranging spending review to be conducted over the summer.