Anger at the way MPs have exploited their work expenses has grown over the practice of "flipping" - changing which property the member designates as their second home.

Alistair Darling, the Chancellor, Hazel Blears, the Communities Secretary, Geoff Hoon, the Transport Secretary, Michael Gove, the Shadow Schools Secretary, and Andrew Lansley, the Shadow Health Secretary, are among those who have been accused of profiting from the system.

For years, MPs have been able to claim generous housing handouts from the taxpayer, asking to be reimbursed for mortgage interest, council tax, bills, furnishings and repairs up to a maximum of £24,222 a year. The payments under the Additional Costs Allowance are only available on their second home, which should be the place that they spend the least time.

But evidence from MPs' uncensored expenses claims suggests that a number of MPs have been working the system by claiming for renovating and furnishing one home, then designating another property as their second home and doing up that one as well.

Some have been accused of using the allowance to help them scale the property ladder at taxpayers' expense.

Changing which property is designated as their second home is a simple matter of notifying the House of Commons fees office which oversees MPs' expenses claims. Officials appear to accept an MP's word on trust.

Some have flipped several times, including Ms Blears. She was today reported to be fighting to keep her Cabinet job after it emerged that she had not only claimed on three different properties in the same year - 2004 - but avoided tax on the proceeds.

In March 2004 the Communities Secretary nominated her Salford constituency house as her second home, spending £1,500 on a bed, a TV and a video recorder. The following month she flipped the designation to her flat in Kennington, south London, and began to claim £850-a-month mortgage costs.

She sold the Kennington flat in August for £200,000, but avoided paying £18,000 capital gains tax on the £45,000 profit she made by telling Inland Revenue that it was her main residence, even though it was registered with the Commons as her second home.

In December, after several months in hotels at taxpayers' expense, she bought another flat for £300,000, this time in the trendy London area of Clerkenwell. She lodged claims for the £1,000-a-month mortgage payments and within four months had spent more than £6,500 on furniture. The house is now said to be worth £500,000.

She denies wrongdoing. "I have complied with the rules of the House, the rules of the Inland Revenue and that's the situation as it is," she said.

Mr Darling changed his designation four times in four years, it has emerged. The Chancellor billed the taxpayer £10,000 to furnish a flat in London, while switching his designation back and forth from his grand house in his Edinburgh constituency. The Edinburgh property is currently designated as his second home, while Mr Darling lives rent-free in 11 Downing St.

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