Buying a Home With a Rental Suite: How a Secondary Suite Mortgage Really Works

You find two houses on the same street. One is a plain three-bedroom. The other has a finished basement with its own door, its own kitchen, and a tenant already paying rent every month. Same price — but only one of them helps you qualify.

That is the whole idea behind a secondary suite mortgage. You live upstairs, someone else lives downstairs, and their rent gets counted as part of your income when the lender does the math. It is one of the few ways a buyer can stretch a budget without earning more at work. It also comes with rules that catch people out, and nearly all of them come down to one question: is the suite legal?

What a Secondary Suite Mortgage Actually Is

There is no special product called a secondary suite mortgage. What you have is a regular owner-occupied mortgage on a property with two units, and lenders treat that very differently than a rental you do not live in.

Here is the part most buyers do not know. If you live in one unit of a one- or two-unit property, the down payment rules are the same as a plain single-family home: 5% on the first $500,000 of the price and 10% on the portion above that, up to 95% of the value. The insured price ceiling sits just under $1.5 million as of 2026.

Step up to a three- or four-unit building that you live in and the minimum goes to 10% down, up to 90% of the value. Go past four units and you are into commercial lending, which is a different conversation.

Compare that to buying a rental you do not live in. That needs 20% down at minimum and cannot be insured. So a buyer with $40,000 saved can often buy a house with a legal suite, but not a rental property. Living in it changes everything. If the down payment is the tight part of your plan, start with our guide to how much down payment you actually need.

How Much Suite Rent Lenders Count Toward a Secondary Suite Mortgage

This is where files are won and lost, and the answer is not one number.

On an insured owner-occupied two-unit property, up to 100% of the gross rent from the second unit can be added to your qualifying income. Property taxes and heat for the home may be taken out of the ratio calculation when that approach is used. On a three- or four-unit owner-occupied property, the usual choices are 50% of the gross rent added to income, or a net rental calculation where operating costs come off the rent first.

Move to an uninsured or conventional file and the treatment tightens. Common approaches are counting half the gross rent, or counting the full rent less a vacancy allowance and then offsetting the full cost of the property against it. Two lenders can look at the same tenant and the same lease and land thousands of dollars apart on what you qualify for.

Alternative lenders often go further. Many add back a much larger share of the rent and allow wider debt ratios — roughly 50% GDS and 50% TDS is common on the alternative side, against the 39/44 most banks and credit unions work to. They can also consider credit scores below 600 depending on how the rest of the file reads. The trade-off is usually around 20% down, a lender fee, and a higher rate.

Private lenders sit at the far end. They care about the equity in the property and the exit plan more than the rent roll, and they generally want 20% to 25% or more down.

None of that means one path is the right one. It means the same house can produce very different approvals, and the work is matching your file to the lender who reads it most generously.

Legal, Legal Non-Conforming, or Illegal: The Difference That Decides Your Approval

Suites fall into three buckets, and the label matters more than the finishings.

• Legal or registered. Built with permits, inspected, and allowed under the local zoning — fire separation, proper egress windows, and whatever else the municipality requires. Lenders count the income without much argument.
• Legal non-conforming. Built legally under older rules and allowed to stay, even though today's bylaws would not permit it. Usually fine, but each lender takes its own view.
• Illegal or unregistered. No permits, no municipal record. Most lenders will not count a dollar of the rent, and some will not lend on the property at all.

There is a second trap here that has caught a lot of buyers. Appraisers in Canada have tightened up on providing market rent figures for suites that do not conform. If your file depends on an appraiser's rent estimate rather than a signed lease, and the suite is not properly registered, that estimate may simply not be available. The deal does not fail because a lender said no. It fails because nobody will put a rent number on paper.

Suite rules are set by your city or town, not by Ottawa, so what counts as legal in one municipality is not automatically legal in the next one. Before you write an offer on a house because of the basement, check whether that suite is on the municipal record. It takes one phone call and it is the most useful thing you can do.

What Lenders Will Ask You For

1. A signed lease for the suite, if it is already rented. Month-to-month arrangements usually need something extra, like a tenant acknowledgement or a few months of bank statements showing the deposits.
2. A market rent estimate from an accredited appraiser if the suite is vacant. This often comes as a rent schedule attached to the appraisal.
3. Proof the suite is permitted — a development or building permit, a suite registry listing, or written confirmation from the municipality.
4. Rental history where the lender wants it. Some look for a track record on the unit rather than a brand-new lease written the week of closing.

One more point worth knowing: short-term rental income on the property you are buying is generally not counted. If the plan is to list the basement by the night, do not build your qualifying math around it.

Mistakes Buyers Make With Suite Income

Assuming the rent covers the payment. It helps, sometimes a lot. But no lender hands you credit for the full rent on every program, and the money you actually collect is not the money they use.

Buying the suite before checking the permits. People fall for a finished basement and find out after the inspection that the city has no record of it. Make it a condition of your offer.

Forgetting the suite costs money too. Insurance goes up on a two-unit home. Utilities, repairs, and the odd empty month are real. A suite is a small business.

Planning to build the suite later and qualify on it now. Rent that does not exist yet does not count. If the plan is to renovate, ask about an improvement program that rolls the work into the mortgage — our guide to a purchase plus improvements mortgage walks through how that is structured.

Only asking one lender. Given the spread in how rent gets treated, one answer is not the answer.

How Gold Lion Mortgages Can Help

We do a lot of these files, and the first thing we do is not an application. It is a straight look at the property and your income to work out which lender reads that suite most favourably, and whether the suite is going to hold up under review at all.

Sometimes the file is a clean insured deal at 5% down with the full rent counted. Sometimes the suite is unregistered and the right move is to qualify without the rent and treat it as a bonus. Sometimes an alternative lender with wider ratios gets a self-employed buyer into a two-unit home a bank would not touch. We will tell you which one you are, and what the difference costs.

Our investment property mortgage page covers financing for properties you do not live in, and the investment property mortgage guide goes deeper on rental offsets and portfolio limits. We work with clients across Canada.

Call (587) 740-0048 or visit goldlionmortgages.com/apply. The first conversation is free, and it is worth having before you write an offer.

Frequently Asked Questions

Can I use basement suite income to qualify for a mortgage?

Yes, if the suite is legal and you can document the rent. On an insured owner-occupied two-unit property, up to 100% of the gross rent can be added to your qualifying income, and property taxes and heat may be removed from the ratio calculation. Uninsured files usually count less. If the suite is not registered with the municipality, most lenders will not count it at all. CMHC sets out the rental income approaches that insured files follow.

How much down payment do I need for a house with a legal suite?

If you live in one of the two units, the minimum is the same as any owner-occupied home: 5% on the first $500,000 and 10% above that, with an insured price ceiling just under $1.5 million as of 2026. A three- or four-unit property you live in needs 10% down. A rental you do not live in needs at least 20% and cannot be insured.

Does the suite have to be legal for a lender to count the rent?

In almost every case, yes. Legal and legal non-conforming suites are generally accepted, though each lender applies its own view to non-conforming ones. Unregistered suites are the problem — most lenders ignore the income, and appraisers have become reluctant to provide a market rent figure for a suite that does not conform. Check the municipal record before you commit.

Will a lender count Airbnb income from my basement?

Generally not on the property you are buying. Short-term rental income on the subject property is excluded by most lenders, and where any short-term income is considered at all, it is usually on other properties you already own with a solid history behind it. Plan your qualifying math around a long-term lease.

What if my credit or income does not fit a bank for a two-unit purchase?

There is usually still a path. Alternative lenders work to wider debt ratios, roughly 50% GDS and 50% TDS, can consider credit scores below 600 depending on the whole file, and often use business bank statements for self-employed buyers. Expect around 20% down and a lender fee. Private lenders focus on equity and typically want 20% to 25% or more down. Our B-lender mortgage guide explains how the alternative side works.

Published: July 29, 2026. Mortgage guidelines, lender programs, and qualifying requirements change. Contact Gold Lion Mortgages to confirm current requirements for your file.

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