Senators have until the end of today to decide whether to pay back dubious expenses flagged by the auditor general, or challenge the audit's findings before a special arbitrator.

Today marks the end of a 10-day grace period for senators named in the auditor general's report to decide whether to repay their questioned claims, or seek to have them quashed by former Supreme Court justice Ian Binnie.

The names of those senators are expected to be made public this afternoon, but there are already several to cross off the list.

Four of the most influential senators — Speaker Leo Housakos, his deputy Nicole Eaton, government leader Claude Carignan and Liberal leader James Cowan — have already repaid about $20,000 in questionable claims.

Former Speaker Noel Kinsella paid back about $9,400 including a $5,663 tab for a trip he and his wife took to his brother-in-law's funeral.

Also this week, Conservative Sen. Janis Johnson repaid the $22,706 the auditor general said she owed for questionable travel claims.

Much like her colleagues, Johnson said she had done nothing wrong, but wanted to repay the Senate out of concern that the arbitration process will increase the costs to taxpayers.

The auditor general's report cost $23.6 million, and identified almost $1 million in dubious housing, office and travel expenses. Nine senators have been referred to the RCMP for a criminal investigation, while 21 more flagged with problematic claims could also face a similar probe if the Mounties choose to follow up.

Data provided by the Senate show that repayments of almost $109,000 had come in as of Thursday afternoon. That leaves almost $884,000 outstanding.