MPs are failing to settle their bar bills after wining and dining in the Commons, it has been revealed.
Some have run up bills of hundreds of pounds in the bars and restaurants, which already enjoy a £5.8 million subsidy from the taxpayer.
The Taxpayers' Alliance said the backlog was "unacceptable", while the MPs were told to lead by example by the British Hospitality Association.
A spokeswoman said: "A bar tab is a service that is often provided for customers, although bills are usually settled at the end of the night. It would be a special privilege for customers as valued regulars to have their bills carried over for any longer than that.
"However, three months of unpaid bills is too long and MPs need to set a good example and pay up on time.”
The latest list published under the Freedom of Information Act by the House of Commons authorities shows one MP, Tory Neil Carmichael, had £604 outstanding for more than three months.
The total was built up in the Strangers Dining Room, the Members Dining Room, the Adjournment and the ornate Pugin Room.
Carmichael told The Huffington Post UK some bills belonging to an MP with a similar name had been mistakenly charged to his account.
He was responsible for some of the costs, he said, but added: "They were putting down his costs onto mine and I thought that was not appropriate and stopped paying it."
He said the matter had now been resolved.
Another Conservative MP, Karen Bradley, failed to settle a tab of £244.
Bradley, a vice chair of the All Party Parliamentary Beer Group, ran up the bill in the Adjournment, Members Dining Room, Members Smoking Room and the Pugin Room.
Her husband Neil, who works for her, said this was explained because the House authorities had failed to process up-to-date bank details she had provided them with.
The MPs' total outstanding bills came to almost £1,400 when the list was published.
When they use Parliament's catering outlets, MPs are expected to pay by cash, like the rest of the staff, unless they hold a an account, which allows payment to be taken from a designated bank account.
The Commons has only pubilshed details of bar bills unpaid for three months or more, saying to release the full list would breach the Data Protection Act.
Fifteen MPs have been named in the latest list, including Respect MP George Galloway, who the documents said had not settled a £10.55 bill from the Pugin Room.
Ron McKay, who works for Galloway, said: "He doesn't owe £10.55, that bill was paid weeks ago."
Justice Minister Helen Grant left a £7.45 tab, while Tory MP Ben Gummer let a £69.50 dining room bill run for over three months.
Labour's George Howarth left a £112.50 tab from the Churchill Room for over three months.
In the past, the Commons has been accused of trying to block publication of the bar tabs, and its release was controversially delayed until after the 2010 General Election.
Responding to the Freedom of Information Act, the House of Commons authorities said: "Payment delays can arise where charging card details or personal accounts themselves have lapsed, or questions have been raised on individual transactions."
Matthew Sinclair, the chief executive of the Taxpayers’ Alliance, said: "It’s unacceptable for MPs to leave these debts racking up and unpaid for so long.
“Such behaviour is not tolerated by the tax authorities and would be equally unheard of in the private sector, so these MPs need to buck their ideas up and pay what is due.
“Taxpayers are angry enough that our politicians keep hiking the tax on drinks, without having to sit back and underwrite the unpaid bills on already subsidised food and drink.”