Multigenerational home in Québec: tax credit and permits

Creating a unit for an aging parent or an adult child, in the basement, a garage or an addition, is what Quebecers call a “maison bigénération” or intergenerational home. Two questions come before the plans: the tax help, and what your city allows. This guide summarizes the Canada Revenue Agency (CRA) page on the Multigenerational Home Renovation Tax Credit (MHRTC, line 45355, modified January 20, 2026), the City of Laval page on adding an additional unit (in French) and Terrebonne’s bylaw 2611, all read on November 3, 2026. For your own tax situation, contact the CRA or a tax professional.

1. The federal credit: how much

For the 2025 tax year, the CRA describes a refundable credit of 14.5% of eligible expenses, up to $50,000 of expenses for each qualifying renovation, or at most $7,250 per claim. It is for creating a self-contained secondary unit that lets a senior, or an adult eligible for the disability tax credit (DTC), live with a relative.

2. The conditions

• The secondary unit: a self-contained unit with a private entrance, kitchen, bathroom and sleeping area, either new or created from a space that did not already meet local requirements, and compliant with local permits, codes and bylaws. It can be a separate structure on the same lot.
• The person it serves: 65 or older at the end of the year of the renovation, or aged 18 to 64 and eligible for the DTC. Only one renovation can be claimed for that person in their lifetime.
• The relative: 18 or older, a parent, grandparent, child, grandchild, brother, sister, aunt, uncle, niece or nephew of the person or of their spouse.
• Timing: the renovation must be completed in the year of the claim, and the home lived in, or expected to be, by the person and a relative within 12 months after the work ends.

3. Eligible expenses

According to the CRA, reasonable expenses directly related to the renovation count: professional labour (electricians, plumbers, carpenters, architects), materials, fixtures, equipment rentals, plans and permits. If you do the work yourself, your own labour and tools do not count. Also excluded: routine maintenance, household appliances, entertainment electronics, financing costs, reimbursed expenses, expenses without receipts, and those already claimed under the medical expense credit or the home accessibility tax credit. Work by a related person counts only if they are registered for GST/HST.

4. In Laval: the additional unit

The City of Laval requires a permit before creating an additional unit, also called an accessory dwelling unit (UHA), in an existing single-family house. It lists three layouts: an addition, a converted attached garage and a finished basement. A fully detached unit is not allowed, and the unit is allowed only in a single-dwelling house. It may connect to the main dwelling or open onto a shared hall, and a separate entrance door may be placed on any façade. An extra parking space is not required.

The base fee is $732 for the additional unit, plus $92 for the first $20,000 of work and $2.50 per $1,000, and the service connection costs $450 for the first dwelling plus $20 per additional unit. The application includes among other things a full architect’s plan, with emergency exits, fire resistance, ceiling height and sound insulation; in a semi-detached or row building, the party wall must be a firewall. In a flood zone, a basement unit could be prohibited.

5. In Terrebonne: a property tax credit

Bylaw 2611 (in French), adopted on July 14, 2026, creates a tax credit for intergenerational accessory units. The owner must live in the house, the unit must be occupied by a direct-line relative of the owner or spouse, or a brother or sister, a permit or certificate must have been issued, and the occupancy declaration must reach the taxation department before June 15 of the year. The credit is limited to the service taxes (waste, water and sewer) of the accessory unit, is renewed each year and is not retroactive.

6. The work

Keep every invoice: the CRA refuses expenses without receipts. Check the RBQ licence of each company, and see home adaptation if the person needs accessibility work. In Montréal’s open permit data (in French), 18 permits issued from October 27, 2025 to October 26, 2026 mention an additional or accessory dwelling unit, 8 of them in Saint-Laurent. See renovation companies in Laval, in Terrebonne or in Saint-Laurent, or describe the unit you want to build to get quotes.