Research suggesting the Government "wasted" more than £120 billion last year has been condemned by trade unions for including nurses' salaries and benefits for better-off families and pensioners.
The TaxPayers' Alliance - which campaigns for lower taxes - said it believed that one in every six pounds of public spending was unwarranted.
Ending the waste would save enough to pay the average household's energy bills for three years or write off the deficit with money to spare, it suggested in its latest analysis.
Offices left empty, an aborted TV series, lost military spares, unused Olympics hotel rooms, a whisky tasting event, pot plants and the hiring of a bunny outfit were among the bills it criticised.
But around a fifth of the total "waste" was identified as the "£22.5 billion cost to taxpayers of overpaying on public sector pay and pensions compared to the private sector".
Other significant factors were given as £8.9 billion in extra housing benefit caused by the "broken" planning system, £2.7 billion paid out in " contributory benefits for those who don't need them" and £2.3 billion spent on " income-related benefits going to the richest fifth of households".
The calculations drew strong criticism from TUC general secretary Frances O'Grady.
"These made-up numbers are based on extreme views such as every nurse is overpaid and that people who have worked hard and paid into the system should not get benefits," she said.
"It's a spectacular own goal."
The TPA's total "waste" sum - the equivalent of £4,560 per UK household - is two and a half times the amount it calculated when it was founded a decade ago - an increase it put down to more public spending being published and a large increase in overall spending.
Other major items included:
:: £20.6 billion in public sector fraud.
:: £1.9 billion on foreign aid due to the international development budget being protected from cuts.
:: £1.6 billion in sick pay due to higher rates of absence among public sector workers.
:: £1.4 billion paying GPs more than their French counterparts
:: £1.2 billion on NHS clinical negligence payouts
:: £1.1 billion in "excessive subsidies to train operating companies".
The cost of missed hospital appointments was also included in the total.
TPA chief executive Jonathan Isaby said: "We need a War on Waste if taxpayers are to secure a better deal from the endless layers of government which are spending their hard-earned money.
"Politicians and bureaucrats are still squandering our cash while families struggle with punishing levels of taxation.
"Rooting out that wasteful spending once and for all will mean that more money can be left in the pockets of taxpayers, who are by far the best judges of how their own money should be spent."
A Cabinet Office spokeswoman said: "We are determined to spend taxpayers' money efficiently and so, as part of our long-term economic plan, we are tackling the waste in Whitehall.
"Last year alone we saved £10 billion but hard-working people expect us to do more and we will".