Parliamentary Standards Commissioner Sir Philip Mawer has reportedly queried ministers' use of housing allowances.
MPs use allowances to pay for second homes
MPs for constituencies outside central London are entitled to up to £22,110 a year to pay for a second home, which most use to fund a London flat.
But some senior ministers have free official residences and use the allowance for their constituency home.
"Any member... ought to pay for at least one house," the Times quoted Sir Philip as saying.
The commissioner told the newspaper: "There has been some concern in the past that, in the case of ministers, they may have a provided home which they are not paying for, they are claiming a parliamentary allowance on a home in the constituency and they are renting out the flat in London which they occupied before they became a minister."
Sir Philip also suggested that the level above which MPs should have to furnish a receipt for expenses should drop to £50 per item from £250 per item.
He told the Times: "That figure is too high. I do think the figure ought to be significantly reduced."
The commissioner, currently investigating allegations that Tory MPs misused House of Commons dining rooms to raise party funds, said the guidelines on such matters should be made clearer.
Sir Philip has made a series of recommendations to the Senior Salaries Review Body, which is undertaking a study of MPs' pay and allowances.