Justice France Charbonneau is expected to give a closing statement.
Then Charbonneau and her fellow commissioner, Renaud Lachance, will have until April 19 to produce a final report for the provincial government.
Liberal premier Jean Charest was forced to launch the inquiry in 2011 after months of pressure from opposition parties.
Journalists from CBC French-language network Radio-Canada's investigative program Enquête were the first to report on many of the corruption allegations that were eventually exposed before the commission.
But it was a leaked report from anti-collusion investigator and former Montreal police chief Jacques Duchesneau in fall 2011 that eventually forced Charest's hand.
Duchesneau alleged a vast network of money-laundering, bid-rigging and kickbacks perpetrated by politicians, union officials, construction executives and organized crime.
He eventually repeated many of the allegations during explosive testimony before the commission in June 2012.
Some of Duchesneau's allegations were backed up by insiders such as former construction boss Lino Zambito.
Zambito testified in September 2012 that about a dozen companies colluded to inflate the price of municipal contracts when he first broke into the Montreal market.
Zambito also said municipal politicians and mobsters were in on the scheme.
As the commission heard more corroborating testimony, well-known public figures began to resign.
Former Montreal mayor Gérald Tremblay was the first to go in November 2012.
Although Tremblay was never directly implicated in any corruption scheme, many accused him of wilful blindness and he quit after mounting pressure.
Less than a week later, Laval mayor Gilles Vaillancourt followed suit.
Vaillancourt was later arrested and is now facing charges of fraud, conspiracy, breach of trust and gangsterism.
Several other municipal politicians from Montreal and surrounding communities also resigned, and some are facing charges.
The commission also exposed ties between Quebec's construction unions and organized crime.
The president of the Quebec Federation of Labour, Michel Arsenault, stepped down in November 2013 in part because of the allegations.
Arsenault's friend and colleague Jocelyn Dupuis was found guilty of fraud and forging documents in September. Dupuis is now appealing that conviction.
The commission also heard allegations of a massive fraud in the awarding of a contract to build the new McGill University Health Centre superhospital in Montreal.
Former MUHC CEO Arthur Porter is accused of accepting part of a $22.5-million bribe to award the contract to engineering firm SNC-Lavalin.
Porter and top executives from SNC are now awaiting trial on several charges.
The final star witness at the commission was former construction boss Tony Accurso, who testified in September, after fighting for months in court to try to avoid appearing as a witness.
Accurso admitted to participating in illegal campaign financing, but denied allegations of influence peddling.
Accurso cast many of his actions as helping to promote Quebec's economy.
Columnists and observers criticized commission lawyers for failing to pin down Accurso on many specific allegations.
Provincial politicians have emerged from the commission largely unscathed.
Although several former Liberal and PQ cabinet ministers were called to testify, including former Liberal deputy premier Nathalie Normandeau, there was no "smoking gun" linking provincial politicians directly to corruption allegations.