DUP MP Ian Paisley Jnr ran up almost £14,000 on his official credit card in expenses debts, it can be revealed.
Figures disclosed in response to a Freedom of Information (FOI) request by the Press Association found that the North Antrim MP owed £13,833.38 on his card on June 29.
He previously had his card blocked when his tab hit £6,195.94.
The Independent Parliamentary Standards Authority (Ipsa) issues MPs with credit cards for to pay for items including travel and accommodation.
The politicians then have to prove the spending was genuine by the end of the month, or they build up debts to the watchdog.
A spokesman for Mr Paisley said: "This figure was a result of unreconciled invoices. The matter was addressed with IPSA earlier this week."
According to the FOI response, Ipsa has suspended the cards of 19 MPs since the beginning of this year because they have not settled outstanding sums.
The debts were then recouped by not paying out valid claims filed by the politicians.
Work and Pensions Secretary Iain Duncan Smith had his official credit card suspended after running up more than £1,000.
Mr Duncan Smith's card was blocked when he owed £1,057.28. He does not currently have any debt.
Others to have their cards suspended included his Labour opposite number Rachel Reeves, who owed £4,033.63 at the time.
Disgraced former Labour MP Eric Joyce, who assaulted a fellow MP in a Commons bar, had his card blocked when he owed £12,919.61, and later had his salary docked.
All have since cleared their debts.
An Ipsa spokesman stressed that the debts from June 29 were a "snapshot".
"An MP may owe an amount to Ipsa for many different reasons, and the fact that an amount is owed does not, in itself, indicate any misuse of the MPs' Scheme of Business Costs and Expenses," the spokesman said.
"As part of our credit management programme, MPs are sent financial statements detailing their monthly position with Ipsa. Where MPs have amounts owed to Ipsa, action is taken to recover these amounts."
