The home secretary says her sister's home in London is her main residence
Home Secretary Jacqui Smith has denied breaking any rules by claiming "second home" expenses for the house she shares with her husband and children.
Ms Smith can claim up to £24,000 a year for that house in Redditch because she has told the Commons her sister's house in London is her main residence.
Ms Smith stays at her sister's home when she is London - normally Monday to Thursday - the Mail on Sunday reports.
A spokeswoman for Ms Smith said she had "fully abided" with expenses rules.
The newspaper says that Ms Smith has claimed more than £116,000 in second home expenses - known as the Additional Costs Allowance - over several years.
The allowance is to help cover the cost of MPs having to have a second home - or place to stay - in London if their constituency is too far away to allow commuting to Parliament.
It can cover mortgage interest, fuel bills and things like a new kitchen, bathroom or even the purchase of items such as flat screen televisions and fridges.
The rules state that the main residence is where the MP "spends more nights than any other".
Under the rules, which have been in the spotlight over the past year, Parliament leaves it up to MPs to decide whether their London or constituency home is their "second home".
A spokeswoman for Ms Smith said: "The home secretary has always abided fully with Parliament's clear rules on expenses and has long-standing written approval from the Parliamentary Fees Office for any agreed expenses.
"She spends the majority of her time in London attending to government business and has full approval for any associated expenses relating to her second home in her West Midlands constituency."
The Mail on Sunday also says that Ms Smith qualified as home secretary for a "grace and favour" home in Whitehall - which if she took would mean she could not claim for a second home.
Ms Smith's spokeswoman told the paper she had not taken that option because "she has lived with her sister in London since she was a backbench MP and is perfectly happy with it. Most people would think that is a nice thing".
The spokeswoman added that Ms Smith pays more than a "peppercorn" rent at her sister's London home.
Liberal Democrat MP Norman Baker, who is the party's Transport spokesman, said he intended to ask the Commons authorities to look again at the designation of first and second homes.
He said: "While Ms Smith may have kept to the rules, she has not stuck to the spirit of the regulations.
"Most of the members of the public looking at this case will conclude that if the home secretary lives in Redditch that's where her house is, that's where her family is, and that's not her second home.
"In my view there ought to be a simple question... put to members of parliament, where do you spend most of your time, where are your children going to school, where do you regard as your base, other questions like that - such as where is your family?"
The rules over designating a main residence were recently clarified after a complaint about Ms Smith's cabinet colleagues Ed Balls and Yvette Cooper.
They were cleared in October of any wrong-doing over earmarking their constituency home in Yorkshire as their main residence rather than their London home.
In his ruling on that case standards commissioner John Lyon said it was difficult to determine which home MPs should claim as their main home.
The complainant had said the London home should be their main residence as that was where their children went to school but Mr Balls and Ms Cooper had suggested "among other things that where they ate Sunday lunch is significant".
Mr Lyon concluded his report by saying that the "normal criteria" that the main home should be where an MP spends more nights than anywhere else should remain the "reasonable general test".