How to Finance a Plex in Montréal: Duplex, Triplex and Fourplex Mortgages (2026 Guide)

The Montréal plex — a duplex, triplex or fourplex with stacked units and outdoor staircases — is one of the most practical ways to own property here. Live in one unit, rent the others, and the tenants help carry the mortgage. But plexes are financed differently from single-family homes, and the details decide how much you can buy and whether you can buy again.

Down payment rules by number of units

Mortgage insurance is only available up to a purchase price under $1.5 million. Québec charges a 9% tax on the insurance premium, payable in cash at the notary.

A worked example: an owner-occupied triplex

Say you buy an $850,000 triplex in Rosemont and live in one unit. With 10% down ($85,000):

• Mortgage before insurance: $765,000
• CMHC premium at 3.10%: $23,715, added to the mortgage — total $788,715
• Québec tax on the premium (9%): $2,134, paid in cash
• Monthly payment at 4.34% over 25 years: about $4,295
• Montréal welcome tax (2026): $12,349, paid in cash a few months after closing

If the two rented units bring in $1,650 and $1,450 a month, the $3,100 in rent covers most of the payment — before property taxes, insurance, heating, maintenance and vacancies. Run your own building through the plex cash-flow calculator.

The same building bought as a pure rental would need $170,000 down (20%). The $680,000 mortgage would cost about $3,703 a month over 25 years, or $3,366 over 30 years where the lender allows it.

How lenders count the rent

This is where plex financing gets interesting. Lenders generally use one of two methods:

• Add-back: a percentage of the rent (often 50% to 100% depending on the lender and the property) is added to your income before your debt ratios are calculated.
• Offset: the rent is subtracted from the property's own costs — mortgage, taxes, heating — so a building that carries itself doesn't count against you.

The same triplex can leave you with very different borrowing room for your next purchase depending on which method your lender uses. If you plan to own more than one property, choosing the lender for its rental method — not just its rate — is often the most valuable decision. We explain this in detail on our real estate investors page.

What lenders want to see

• Signed leases for every unit, and a rent roll if the seller provides one
• Recent municipal and school tax bills
• An appraisal — lenders value plexes on comparable sales and, increasingly, on income
• For older buildings: the condition of the roof, electrical panel, plumbing and heating system
• Your income documents and down-payment proof, as for any purchase

Rent increases in Québec are regulated by the Tribunal administratif du logement, so lenders underwrite the leases in place, not the rents you hope to achieve after renovations.

Five units and more: commercial rules

Buildings with five or more units are underwritten as commercial multi-residential properties. The lender focuses on the building's net operating income and debt-service coverage ratio (typically 1.1 to 1.3 times), asks for operating statements, and may use CMHC-insured multi-unit programs that allow longer amortizations. The process is heavier, but well-run buildings can obtain excellent terms. Our commercial financing page covers the process.

How to estimate a plex's real cash flow

Rent is only half the equation. Before you rely on a building to carry itself, subtract every recurring cost from the rent roll:

• Municipal and school taxes — check the latest bills, not the listing estimate.
• Insurance — multi-unit buildings cost more to insure than single-family homes.
• Heating and electricity if they're included in any lease.
• Maintenance and repairs — a reserve of 5% to 10% of rents is a common rule of thumb, more for older buildings.
• Vacancy — even in a tight market, budget for a few weeks between tenants.
• Management, if you won't manage the building yourself.

Lenders run a similar calculation. If the numbers only work with today's lowest rate, stress-test them at a renewal rate one or two points higher before you commit.

Undivided co-ownership and condo conversions

In Montréal you'll often see plex units sold in undivided co-ownership (indivision), where several owners share one title for the whole building. Fewer lenders finance these, and they usually require a larger down payment and a solid co-ownership agreement. Buildings converted to divided co-ownership (condos) finance like condos, but conversions of rental buildings in Montréal are tightly regulated, so check the building's status before you count on a conversion strategy.

Renovating after you buy

Many plexes need work. Some lenders offer purchase-plus-improvements programs that add the cost of renovations to the mortgage, with the extra funds released when the work is completed and inspected. You need quotes from contractors before closing, and the improvements must add value. For larger projects, a refinance after the work is done — based on the new value — can recover part of the money you put in. See our home equity calculator to estimate what a higher appraisal would release.

Owner-occupied vs. rental: lender and tax differences

Living in one unit gives you access to insured financing, lower down payments and often better rates. It also affects tax: rent from the other units is taxable income, and a share of expenses — including mortgage interest on the rental portion — is generally deductible. If you later move out and rent your unit too, both your lender and your accountant need to know, because the property's use has changed. Keep records from day one.

A simple plex buying checklist

1. Get pre-approved with rental income counted, not just your salary.
2. Collect the leases, rent roll and tax bills before your offer's financing condition starts.
3. Book an inspection that covers the roof, electrical, plumbing and heating.
4. Run the cash flow at today's rate and at a higher renewal rate.
5. Budget the welcome tax, notary fees and a repair reserve in cash.

Mistakes plex buyers make

• Budgeting on projected rents instead of the leases in place.
• Forgetting the welcome tax and the 9% tax on the insurance premium in the cash-to-close.
• Choosing the lowest rate from a lender whose rental-income method blocks the next purchase.
• Underestimating repairs on older buildings — keep a reserve.

Thinking about a plex? Book a plex financing review and we'll model the building, the down payment and the lender options before your financing condition expires.