Liz Truss is facing calls to turn down the allowance of up to £115,000 a year she will be entitled to as a former prime minister.
The Liberal Democrats said it will leave a "bitter taste" if she claims the payment in the wake of her brief and tumultuous tenure in Downing Street.
The public costs duty allowance was introduced in 1991 in the wake of the resignation of Margaret Thatcher to support former prime ministers in their public duties after they leave office.
However Lib Dem cabinet office spokeswoman Christine Jardine said it would be "unconscionable" if Truss were to receive it after such a short time in office.
"Liz Truss will forever be known as the 50-day prime minister. There is no way that she should be permitted to access the same £115,000-a-year for life fund as her recent predecessors - all of whom served for well over two years," she said.
"To make matters worse, Truss's legacy is an economic disaster - for which the Conservatives are making taxpayers foot the bill. For Truss to walk off into the sunset with a potential six figure dividend, while leaving the British public to suffer, would be unconscionable," she added.
"This huge potential pay out will leave a bitter taste in the mouth of the millions of people struggling with spiralling bills and eye-watering mortgage rate rises thanks to the Conservatives' economic mismanagement," Jardine added.
