Several MPs intend to challenge requests they repay money following an independent review of expenses claims.
Auditor Sir Thomas Legg has reviewed second homes expenses claims since 2004 and applied new annual limits on those for gardening and cleaning.
One MP, Labour's Bill Etherington, has said he will not repay money if he feels it was justifiable at the time.
Tory leader David Cameron has said he will withdraw the whip from any of his MPs who refuse to pay when asked, BBC News reports.
It was also reported, Sir Thomas Legg has explained his interpretation of Commons rules and his responsibilities auditing parliamentary expenses in a seven-page note to MPs.
The note explains that for most of the Additional Claims Allowance claims that Sir Thomas considered, he adopted a narrow and methodical approach, much like that of an accountant auditing a company’s books.
Mostly, that meant ensuring that the paperwork submitted to the Commons authorities fully substantiated the claims made. Where paperwork appeared inadequate, Sir Thomas wrote to MPs requesting more information, Telegraph.co.uk reports.
It was also reported, senior MPs cast doubt on the legal basis for retrospective claim limits and are suggesting that the audit of their Additional Cost Allowances has been rushed and inaccurate, despite pressure from whips to fulfil Sir Thomas’s requests immediately
In the meantime, today, Mr Cameron warned his party that MPs failing to repay expenses would not be allowed to stand as Conservatives in the general election expected next year.
"In the end, if people are asked to pay back money and if the authorities determine that money should be paid back and they don’t pay it back, in my view, they can’t stand as Conservative MPs, that is the minimum point," Mr Cameron said.
"One point is important: this is a process. You get a letter, in the letter it says ’this is provisional’ and you have to reply to the letter, and there will be some issues of determination about whether it is correctly described and all the rest of it. But at the end of the process, MPs have to pay back the money they are asked to by the authorities. To me, that is the least we can do to try and sort out these problems of the past before going on to the future," Times Online reports.