Ms Smith says the claims she has made are above board
The parliamentary standards watchdog has dismissed complaints about Home Secretary Jacqui Smith's expenses.
John Lyon will not investigate claims made about her use of the second homes allowance for MPs.
His office had had a "fair amount of correspondence" but a spokeswoman told the BBC "there is not sufficient evidence for an inquiry".
Ms Smith has said her claims for second home expenses on her family home while were "all above board".
'Case to answer'
Ms Smith reportedly claimed £116,000 in expenses for her home in Redditch, Worcestershire, after telling the Commons that her sister's home - where she stays while in London - was her main residence.
In a letter to Mr Lyon on Monday, Harry Cole, of the Centre for Open Politics, said there appeared to be "prima facie a case to answer in respect of Jacqui Smith's arrangements" and urged him to open an inquiry.
But the office of the Parliamentary Commissioner for Standards said Mr Lyon would not be pursuing the complaint.
The Conservative MP Ben Wallace also complained to Mr Lyon, however a spokeswoman said on Tuesday afternoon that this complaint had also been rejected.
Earlier, Ms Smith said she had checked with the parliamentary authorities about the arrangement and had "received assurances" it was allowed.
She added: "I have abided by the rules. Everything I have done is above board."
But Conservative leader David Cameron told a news conference on Monday that the arrangement did "not look very good".
'Value for money'
The tax-free Additional Costs Allowance - worth up to £24,006 a year at present - is claimed by MPs for the costs, such as mortgage interest and fuel bills, of working in both Westminster and a constituency.
Under the rules, the main residence is where the MP "spends more nights than any other" although recent guidance said "value for money" for the taxpayer could be used as a factor if there was doubt which home that was.
It has been reported that Ms Smith stays at her sister's home when she is London, normally between Monday and Thursday.
The home secretary told GMTV: "I took the decision that it was best for my kids to be where they grew up, where they were born, where they go to school - back in my constituency.
"But, as home secretary, I obviously have to spend the bulk of my time in London. That's what I thought would work best for me in terms of my job and for my family."
But Lib Dem MP Norman Baker has written to the Commons Speaker asking that second homes allowance rules be reconsidered.
His letter said: "A 'pied-à-terre' in London, or a room in a relative's house, cannot sensibly be regarded as a main residence. It is clearly a second residence.
"Yet this test seems not to be applied by all members. Indeed, I understand one member claims that his ancestral castle is his second home, and claims accordingly for the lichen to be removed from its walls. This cannot be right."