OTTAWA - The last sitting senator to owe the Senate money after a critical audit of spending has paid up.

Senate records show that as of late Tuesday, Liberal Nick Sibbeston had repaid the Senate $26,924 that he owed for disallowed expenses.

A special arbitration process headed by former Supreme Court justice Ian Binnie found that Sibbeston billed taxpayers for stays in Edmonton en route to and from his home in Fort Simpson, N.W.T.

The repayment leaves seven former senators still on the hook for more than $527,000 in questionable expenses that the Senate wants to recoup.

Those seven senators have until Friday to repay the amounts in full or face the possibility of being taken to court by the upper chamber.

None of the seven, including retired Liberal Rod Zimmer from Manitoba who owes just over $176,000, opted for the arbitration process the Senate set up for senators who wanted to challenge the findings of last year's auditor general's report.