The Canadian Taxpayers Federation wants the newly appointed Alberta senator to be open about his expenses.
Doug Black was one of five people appointed to the Senate on Friday by Prime Minister Stephen Harper.
Black is a lawyer and former chair of the Board of Governors for the University of Calgary.
In September it was revealed that he had claimed expenses during an 18-month period at the university, totaling more than $28,000.
"He's now going to be completely exempt from any sort of fiscal accountability," said Derek Fildebrandt, of the Canadian Taxpayers Federation.
He adds senators and members of Parliament are also exempt from freedom-of-information requests.
Fildebrandt is calling on Black to be fully transparent.
"By being the first senator to post his expenses online with receipts, he would not only be clearing his name but he'd be setting a great example."
Tom Flanagan, a professor of political science at the University of Calgary and a former Tory advisor, said Black's name is clear because he has paid that money back.
"The book on that is closed. As far as anybody knows, it's an isolated incident in an otherwise very successful career," said Flanagan.
Black was not available for an interview but issued a statement saying he is looking forward to getting started on the work ahead.