Buying a Duplex, Triplex or Multiplex in Ontario: What You Need to Know

Buying a duplex in Ontario sounds straightforward — it's just a house with an extra unit, right? In practice, purchasing any property with two or more self-contained residential units brings a different set of legal and financial considerations than a standard single-family purchase. Zoning rules, tenant rights, lender requirements, and closing costs all shift the moment rental income enters the picture.

Whether you're a first-time buyer hoping to offset your mortgage with a rental unit, or an experienced investor adding a triplex to your portfolio, understanding what's different before you make an offer will save you time, money, and legal headaches on the other side.

Why multiplexes are different from a standard home purchase

The most important thing to confirm early is whether the property is legally permitted to operate as a multi-unit building. A seller may market a property as a "triplex," but if the third unit was finished without a building permit or is located in a zone that only allows two dwelling units, you could inherit a by-law compliance problem. Municipal zoning by-laws in Ontario vary widely — what's permitted in one city may require a minor variance or rezoning in another. Before anything else, contact the local municipality to confirm the zoning designation and that the number of units is legal.

Financing a multi-unit property works differently from financing a single-family home. Lenders treat properties with one to four units as residential mortgages, while properties with five or more units typically fall into commercial lending with different qualification criteria, rates, and terms. Even within the one-to-four-unit category, lenders often apply stricter rules if you won't be occupying one of the units yourself. The way rental income is treated in your qualification calculations also changes depending on the lender and the number of units involved.

Another consideration that catches buyers off guard is the duty of disclosure regarding existing tenants. If the property is currently tenanted — which is common with income properties — you are not buying vacant possession. Ontario's Residential Tenancies Act governs the relationship between landlords and tenants, and those rights don't reset when a property changes hands. The purchase agreement must reflect the reality on the ground: existing leases, current rents, and any arrears or issues in the landlord-tenant relationship should all be disclosed before you firm up.

Step-by-step: what to check before waiving conditions

Due diligence on a multiplex is more layered than on a typical home. Consider the following steps before removing any conditions from your offer:

1. Confirm zoning and legal unit status. Request a zoning certificate from the municipality and verify that every unit is legally recognized. Don't rely on the listing description alone.

1. Review the building permit history. Ask for records showing that any additions, basement conversions, or unit separations were done with permits that were properly closed. Unpermitted work can trigger remediation requirements.

1. Check fire code compliance. Multi-unit properties in Ontario are subject to fire code requirements including interconnected smoke alarms, carbon monoxide detectors, and fire separations between units. A fire inspection report or fire retrofit compliance letter provides certainty here.

1. Obtain and review all existing leases. Every tenancy agreement currently in place must be disclosed. Review the rent amounts, lease terms (fixed-term vs. month-to-month), and any special terms agreed to with current tenants.

1. Request a current rent roll. A rent roll summarizes each unit's current rent, last rent increase, and payment history. Compare it against the leases and ask for evidence that rents are actually being collected.

1. Understand utility separation. Confirm whether each unit has a separate hydro meter, gas meter, or water sub-meter. Shared utilities affect how you'll manage costs as landlord and may affect your financing.

1. Arrange property insurance before closing. Insurers treat multi-unit rental properties differently. Get a quote before you firm up — some older properties or properties with certain construction types can be difficult or expensive to insure.

1. Complete a title search. Your lawyer will conduct a title search, but ensure it captures any easements, work orders, or liens from the municipality that relate to by-law violations or outstanding remediation.

Tenant rights on closing: the Residential Tenancies Act

Existing tenants do not lose their tenancy because the property is sold. Under Ontario's Residential Tenancies Act, a change in ownership does not terminate a lease or give the incoming owner the right to demand a tenant vacate. The new owner steps into the shoes of the old landlord and inherits all existing obligations — including honouring the current lease terms and respecting lawful rent amounts.

If you intend to occupy one of the units yourself, or if a family member will move in, Ontario's rules around "own use" notices are strict. You generally cannot serve a notice to terminate a tenancy for own use (the form known as an N12) until after you have completed the purchase and become the landlord of record. The required notice periods and compensation obligations apply in full, and tenants have the right to dispute an N12 at the Landlord and Tenant Board if they believe it is given in bad faith.

Similarly, if you plan to demolish, convert, or do major renovations that require vacant possession, a different notice process (N13) applies, with its own timelines and tenant protections. Attempting to pressure tenants out informally before closing is not a shortcut — it can expose the seller to liability and complicate your purchase.

Financing a multiplex: what lenders look at differently

• One to four units: Treated as residential mortgages. If you occupy one unit, CMHC-insured financing (with a lower down payment) may be available — as of writing, the rules allow insured financing for owner-occupied properties up to four units, but confirm current CMHC guidelines before relying on this.
• Five or more units: Falls outside residential mortgage rules and into commercial lending. Down payment requirements and interest rate structures are typically less favourable.
• Rental income treatment: Lenders differ on how much of the rental income they will use to offset your debt obligations. Some use a percentage of gross rents; others use net operating income. Ask your mortgage professional to walk you through the specific calculation for each lender you're considering.
• Non-owner-occupied properties: If you won't live in any unit, expect a higher minimum down payment than on an owner-occupied purchase. As of writing, this is generally higher than the minimums that apply to a primary residence — verify current requirements with your lender.

Closing costs unique to income properties

• Land transfer tax applies to the full purchase price, including any value attributable to the rental units. Ontario's land transfer tax (and Toronto's additional land transfer tax, if applicable) can be a significant number on a multi-unit purchase.
• HST considerations: The purchase of a used residential rental property is generally exempt from HST, but exceptions exist — particularly if there is a commercial component, if the property was recently substantially renovated, or if it is newly constructed. If HST applies, it is a material cost that needs to be addressed in the purchase agreement.
• Title insurance: Strongly recommended on income properties, where zoning non-compliance and permit issues are more common.
• Ongoing HST on rents: Residential rents are generally exempt from HST. If you are considering any commercial use of a unit, different HST rules may apply. Verify with a lawyer or accountant.

Frequently asked questions