Lino Zambito told the probe during his sensational testimony this fall that he had been forced to leave the construction industry when legal problems put a financial strain on his business.
Now Zambito may be getting squeezed out of his new career as a restaurateur.
Revenue Quebec announced Wednesday that it had seized $38,465 from his Montreal-area pizzeria because of unpaid taxes, along with equipment.
It said it had also moved to revoke Zambito's right to collect sales taxes — which would limit his ability to own a restaurant.
"The tax-collection certificate is necessary to operate a business," Revenue Quebec spokesman Stephane Dion explained.
Zambito became a household name in Quebec this fall as the witness who produced a memorable breakthrough in the province's corruption inquiry.
He was the first witness to describe a secret cartel where he and others rigged bids on public projects, sharing their extra profits with political parties, corrupt civil servants and the Mafia.
That performance on the witness stand earned Zambito an invitiation to the popular Radio-Canada TV show Tout le monde en parle, where he earned polite applause as he strode to the stage.
His testimony has since been echoed by other witnesses.
Zambito also testified that he struggled to get credit from financial institutions after his name surfaced in corruptions scandals. He was charged with fraud in 2011.
Those problems prompted the longtime sewer specialist to leave construction and open a pizzeria in Blainville, north of Montreal.
Zambito told Radio-Canada on Wednesday that he hadn't actually owned the pizzeria since last month. He declined to reveal whom he had sold it to. But the news organization said he specifically stated that he had not sold it to his ex-spouse for the token fee of $1.
Several people embroiled in Quebec's ongoing scandals, facing the threat of potential property confiscation, have transferred personal property to relatives for a nominal sum.
He told Radio-Canada that he had paid back more than $30,000 that the government claimed, but was involved in a dispute over an outstanding sum that he said had been unfairly demanded.
While he may be getting muscled out by the taxman, Zambito might still look back with fond memories on some of his experiences in the pizza business.
According to online reviews, some people liked his restaurant.
La Pizzeria Etc., Zambito's restaurant, earned positive reviews from 68 per cent of commenters on the Urbanspoon website.
"This is a lot more than a pizzeria," said one of the eight comments. "I've tried the osso bucco which is really good."