Lady Thatcher, the former prime minister, has claimed more than £500,000 in expenses in the last five years, despite her ill health.
The 86-year-old still carries out some public engagements more than 20 years after she left office.
As a former prime minister, she is eligible for a public duties cost allowance to cover office and secretarial expenses.
Cabinet Office figures reveal Lady Thatcher claimed £535,000 since 2006.
Sir John Major, who succeeded her in Downing Street, has received £490,000. He created the fund when he was in power in 1991.
Tony Blair, who beat Sir John in the 1997 election, has been given just under £273,000 from the public purse since 2007.
In 2008-9, he received more from the allowance than he earned from his official salary when he was prime minister the year before.
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