A by-election will be held on April 13, 2026, to elect a member of Parliament (MP) to represent Terrebonne, Quebec, in the House of Commons for the remainder of the 45th Parliament after the riding's result in the 2025 general election was annulled by the Supreme Court of Canada on February 13, 2026, vacating the seat held by the then-Liberal Party MP Tatiana Auguste.
The 2025 federal election result in Terrebonne was contested by the Bloc Québécois candidate, defeated MP Nathalie Sinclair-Desgagné, after a judicial recount awarded the seat to Liberal candidate Tatiana Auguste by one vote. The result was challenged due to a printing error by Elections Canada on a return envelope for mail-in ballots which resulted in an envelope containing a vote for the Bloc Québécois candidate being returned to sender. The Supreme Court of Canada overturned a lower court decision and annulled the result, vacating the seat and requiring a by-election.
A writ for the by-election could be issued no sooner than February 27 and no later than August 1, 2026. Under the Canada Elections Act, the minimum length of a campaign is 36 days between dropping the writ and election day, but must not exceed 50 days. The by-election must also be held on a Monday within that time frame. Accordingly, the earliest possible date for the by-election was April 6 and the latest was September 28.
On March 8, the writ was issued for a by-election to be held on April 13. Nominations close on March 23, at 2 pm local time.
After reviewing its internal procedures, Elections Canada announced that, to avert the possibility of misdirected ballots in future, special ballots will no longer be manually prepared by a riding office, but will be centrally and automatically prepared at its Ottawa office. However, the change was not expected to be fully implemented until the fall.
The candidates in 2025 have reappeared for the by-election:
Auguste and Sinclair-Desgagné had already been confirmed as candidates before the by-election was called.
Conservative Adrienne Charles's candidacy was announced on March 11. The Greens are fielding Benjamin Rankin again, as are the NDP with Maxime Beaudoin. Maria Cantore is also returning for the PPC.
The Longest Ballot Committee chose Terrebonne as their target out of three by-elections being held simultaneously. This resulted in a total of 48 candidates when nominations closed, and Elections Canada announced that write-in ballots similar to those used in Battle RiverâÂÂCrowfoot in 2025 would be employed.
Sinclair-Desgagné used the slogan Une voix qui compte! ("A voice/vote that counts!"). She promoted the Bloc platform for supporting seniors and first-time home buyers, and voiced concerns over the proposed routing of the Alto high-speed rail line and potential expropriations for it in the riding. Local observers note that, besides the issue of the Alto line, other concerns include the construction of new housing and the decontamination of a former DND firing range to make way for a new interchange on Autoroute 640.
Bloc leader Yves-François Blanchet laughed off suggestions that "fake candidates" could be nominated in the concurrent by-elections being held in Scarborough Southwest and UniversityâÂÂRosedale, in order to create extra campaign financing room in the Terrebonne contest.
At a Liberal rally, Auguste's advocate claimed that she had "won fair and square" in 2025, and that the Supreme Court of Canada had later decided that it wanted to punish Elections Canada. At a subsequent Bloc rally, Sinclair-Desgagné described that as saugrenu ("absurd"), and said that people would find it strange that the Liberals would distance themselves from a decision of the SCC where normally it would be embraced by the party. That rally also featured posters bearing the slogan Reprenons notre place le 13 avril ("Let's take back our place on April 13").