Senator Patrick Brazeau has been sent a letter from the Senate notifying him that 20 per cent of his pay will be docked until he has repaid $48,000 in housing and travel expenses he claimed inappropriately.

Senator Gerald Comeau, chair of the Senate committee on internal economy — the body that monitors and regulates senators' salaries and expenses — said the letter was sent Tuesday. Comeau told CBC News the 20 per cent deduction is called a "set-off."

Brazeau failed to meet a June 30 deadline to repay the $48,000. The money was paid out to cover the rent for Brazeau's townhouse in Gatineau, Que., as well as gas mileage for trips to and from Maniwaki, a community 135 kilometres from Ottawa that Brazeau identified as his primary residence.

Brazeau said his Gatineau house, near Ottawa, was a secondary residence he had to maintain for work since Maniwaki is over 100 kilometres from the capital. Senate rules allow senators to charge living expenses in or close to Ottawa if they reside at least 100 kilometres away, although Brazeau claimed only his rent and gas mileage, and not per diems for meals while living in Gatineau.

Could lose $2,000 a month

Brazeau's base salary as a senator is $135,000. Twenty per cent lopped off his pay means he could lose a little over $2,000 a month of his gross salary for the next two years.

On Wednesday, his office said he has not yet received any notification from the Senate about the snipping of his wages.

Brazeau, at 38 the youngest sitting senator, has the right to remain in his Senate seat until he's 75. However, a criminal conviction could cause him to be expelled from the chamber. He is currently facing charges for assault and sexual assault in a case that is before the courts.

Due to the criminal charge, Brazeau was thrown out of the Conservative caucus and suspended from the Senate. But as an Independent senator, he still receives his salary.

Brazeau, appointed on the advice of Prime Minister Stephen Harper in 2009, was one of four senators who were subjected to a forensic audit by the accounting firm Deloitte about expenses. One audit, of Senator Pamela Wallin, is still ongoing.

In Brazeau's case, Deloitte found he spent only 10 per cent of his time in Maniwaki during an 18-month examination period, although Deloitte also said the rules about the definition of  primary residence are unclear.

The Senate committee on internal economy declared the rules were unambiguous and at the end of May ordered Brazeau to pay back $48,000 within 30 days.

Senator Mac Harb was also ordered to repay money by the end of Wednesday, July 3. Senator Mike Duffy was assessed as owing $90,000 but he has already reimbursed the Senate with money given to him by the prime minister's former top aide, Nigel Wright, who resigned when information about the personal cheque became public.