Nearly 3,000 civil servants at HM Revenue and Customs are being paid full salaries despite having no official role, the Tories have said.
In total, £132 million a year is being spent on 4,600 "non-jobs" across the whole civil service, according to government figures obtained by the party.
Shadow Cabinet Office minister Francis Maude said that while millions in private sector jobs were worrying about what the new year would bring, the Prime Minister was "treating Whitehall like a glorified job creation scheme".
A series of parliamentary questions by the Conservatives found that 4,634 permanent staff were "staff without posts". The majority of these - some 2,874 - are employed by HM Revenue and Customs (HMRC) and are known as "pre-surplus staff".
Others include 830 civil servants at the Ministry of Defence, 368 at the Department of Work and Pensions and 212 at the Foreign Office.
Mr Maude said: "The new year brings with it worrying uncertainty for millions in private sector jobs, who are really concerned about what Gordon Brown's recession will mean for their families and the ability to pay their mortgage.
"Yet Labour ministers are treating Whitehall like a glorified job creation scheme.
"Gordon Brown talks about creating 100,000 new jobs, but in reality, public cash is being wasted on government bureaucrats literally doing nothing."
But an HMRC spokeswoman said pre-surplus staff were carrying out "essential work for the department as they await new jobs".
The Tories based their calculations on the average wage bill cost of a civil servant, including National Insurance and pension contributions, of £28,622 - giving an annual bill of £132.6 million.
