You Rented Out Your Basement. Will You Owe Capital Gains Tax When You Sell?
The honest answer forks — and the fork is not how much space you rented. It turns on two things almost nobody checks: did you make a structural change, and did you claim CCA. Get those wrong and a tax-free home sale can quietly become a taxable one.
I rent out part of my home. Will selling it trigger capital gains tax on that portion?
Two owners can both say “I rented out my basement” and get opposite answers at sale — one keeps a fully tax-free sale, the other owes tax on part of the gain. What separates them is not how many square feet they rented; it is whether they made a structural change and whether they claimed CCA (capital cost allowance) on the rented part. Rent a room with a shared kitchen, alter nothing structural, claim no CCA, and the CRA’s practice is to keep the whole property as your principal residence. Wall the basement off into a self-contained unit with its own entrance and bath, and the converted portion is deemed disposed of at fair market value — the gain accruing on it during the rental years can be taxable. Note the first path rests on CRA administrative practice, not a written section of the Income Tax Act.
Source: CRA Income Tax Folio S1-F3-C2, Principal Residence, ¶2.57–2.60.2; Income Tax Act s.45(1)(c), 45(2), 45(3). Current canada.ca version, verified 2026-08.
I’m Arthur Zhao. Here is the version of this question that actually costs people money. A homeowner rents out the basement for years; an accountant mentions claiming a little depreciation to shelter some of the rent; they check the box — and only at closing, years later, do they learn it quietly reached back and made years of gain taxable that would otherwise have been fully exempt.
Most people expect the capital gains question to be about area — rent more of the house, owe more later. It usually isn’t. It turns on whether you altered the structure and whether you claimed CCA. Below I walk the decision test, and — more to the point — the two moves that can turn a tax-free home sale into a partly taxable one. Standard caveat: I’m a broker, not an accountant, so take anything touching your own return to a licensed tax professional.
Why “how much did you rent” is the wrong first question
The common assumption is that the larger the rented share, the bigger the future capital gains bill. But the real dividing line in the CRA’s rules is not the size of the rented share — it is whether the rental changed the nature of the property.
In Income Tax Folio S1-F3-C2, Principal Residence, the CRA splits “part of the home earns income” into two buckets that produce nearly opposite tax outcomes. Which bucket you fall into depends on structural change and CCA. Area only matters later — as an input to the apportionment math once a deemed disposition has actually been triggered. It is not the switch.
Renting a room vs. building a self-contained suite
⚠️Keep “the law” and “CRA practice” separate. The rule that lets you rent a room and keep the whole home as a principal residence rests on CRA administrative practice — the folio literally says “It is the CRA’s practice not to apply…” — and requires all three conditions at once: the income use is ancillary, no structural change, and no CCA claimed. It is not a written exemption in the Income Tax Act. A practice has softer edges than a statute, so hold your own facts up against it carefully.
Test 1 — Was there a structural change?
45(1)(c) deemed disposition: at the moment of change, the converted portion is treated as sold at fair market value and immediately reacquired. When you eventually sell, the gain on that portion during its income-earning years can be taxable.Test 2 — Did you claim CCA?
Test 3 — Only now does “apportionment” enter
The trap that costs the most: CCA reaches back to day one
This is the single most valuable thing to understand here. Many owners claim CCA on the rented portion to shelter a bit more of the rental income in the year. It looks like a tax saving. But folio ¶2.60 is blunt: the moment you start claiming CCA on the income-producing portion, the deemed disposition rule applies as of the time the income-producing use commenced — not from the year you first claimed CCA, but back to the day you started renting.
In other words, the exemption you were preserving by not claiming CCA gets pierced retroactively the moment you do claim it. A small current-year depreciation deduction can convert a slice of gain that would have been fully tax-free on sale into a taxable one. For most owners who live in the home and rent a room or two, claiming CCA is a losing trade. Run the numbers before you check that box.
🚨The CCA retroactivity rule is the easiest landmine here. Once you claim CCA on the rented portion, the deemed disposition is not measured from the year you claimed it — it reaches back to the day you started renting. The exemption you preserved by not claiming CCA gets pierced retroactively. Trading a small depreciation deduction for that is usually a bad deal — model it with an accountant before you file.
💡 My own read: for an ordinary owner-occupier renting out a room or two, the cheapest and calmest path is usually the “no structural change, no CCA” lane. Touch the structure and you slide from ¶2.60 into ¶2.58; claim CCA and you pierce your exemption retroactively. The short-term upside of either move — a full second-suite rent, or a bit more depreciation this year — often does not come close to covering the tax it can cost you at sale. If you genuinely want to convert or genuinely want CCA, model it with an accountant on real numbers first.
A timeliness edge: since 2019, a 45(2) election can cover a partial change
If you did make a ¶2.57-style partial change in use — you really did build that self-contained suite — you are not entirely without a cushion.
Before March 19, 2019, the 45(2) and 45(3) elections that switch off a deemed disposition were only available when the entire property changed use; a partial change could not use them.
Since March 19, 2019, that changed: on a partial change in use, a taxpayer can elect under 45(2) so the deemed disposition that would otherwise arise does not apply; conversely, when an income portion is turned back to residential use, a 45(3) election is available. The election is filed as a signed letter with the return for the relevant year. Older articles written before 2019 simply do not mention this — if your source is silent on it, it is probably out of date. Whether and how to elect is a call for your accountant.
Two things people forget: you still report the sale, and there is no separate Ontario layer
Even if your home was 100% your principal residence the whole time and the entire gain is exempt, since the 2016 tax year you must still report the sale: report the disposition and make the principal residence designation on Schedule 3, and file Form T2091 if it was not your principal residence for every year you owned it. Skipping the report can jeopardize the exemption itself.
On the exemption formula’s “one-plus” rule: the exempt fraction is roughly (years designated as principal residence + 1) ÷ years owned, and that “+1” cushions the year you move, when the old and new homes briefly overlap. It still applies, but since October 3, 2016 the +1 only applies if you were resident in Canada in the year you acquired the property.
Finally: capital gains tax and the principal residence exemption are federal rules under the Income Tax Act, administered by the CRA — Ontario has no separate provincial layer stacked on top. A taxable capital gain (of which 50% is included in income) flows into your Ontario personal income tax with everything else, but there is no “Ontario principal residence exemption” — do not let a local blog’s phrasing convince you otherwise.
The bottom line
Three things you can act on today:
1. Know which side you are on. A room or two, shared kitchen and bath, no structural change, no CCA → most likely the whole home stays a principal residence. A walled-off suite with its own entrance and bath → most likely into the apportionment regime.
2. Be very deliberate about CCA. Claiming it to save a little tax this year can pierce your exemption retroactively — usually not worth it.
3. Keep records and report on time. Document the conversion date, the date renting began, and related expenses; in the year you sell, report on Schedule 3 and make the designation.
Once more, plainly: I’m a broker, not an accountant or tax advisor. This is a framework and a map of the common mistakes, not tax advice. For your specific facts — especially anything involving a conversion, CCA, or a 45(2) election — work with a licensed accountant or tax professional, and rely on the current CRA guidance and your actual circumstances.
- CRA — Income Tax Folio S1-F3-C2, Principal Residence (¶2.57–2.60.2: partial change in use, 45(1)(c) deemed disposition, the CRA three-condition practice, the CCA retroactivity rule, and the 45(2)/45(3) partial-change elections)
- CRA — Reporting the sale of your principal residence (Schedule 3 designation required since the 2016 tax year; T2091 if not your principal residence for every year owned)
- Income Tax Act — s.45 (change in use, 45(1)(c) deemed disposition, 45(2)/45(3) elections), laws-lois.justice.gc.ca
Buyer Feedback After Showing →Turning a Rental Into Your Home: CRA Change-of-Use Rules →Filing Rental Income Tax with CRA Form T776: What Landlords Can Deduct, and Why Claiming CCA Depreciation Can Backfire →Ontario Mortgage Guide →
Frequently Asked Questions
I just rent one basement room to a student and we share the kitchen. Will I owe capital gains tax when I sell?
Usually not. As long as three conditions hold — the rental is merely ancillary to your own use of the home, you made no structural change, and you claimed no CCA on the rented portion — the CRA’s practice is to treat the whole property as your principal residence, so a sale stays fully exempt. Note this is CRA administrative practice, not a written statute; miss any one condition (claiming CCA is the usual one) and it can fall apart. Confirm your own situation with an accountant.
Is renting a room really taxed differently from converting the basement into a full suite?
Yes, and the outcomes are nearly opposite. A shared room or two sits in folio ¶2.60 (ancillary use) and generally does not break your exemption. Walling off the basement into a self-contained unit with its own entrance, kitchen and bath sits in ¶2.58 — a substantial, more-permanent change in use — so the converted portion is deemed disposed of and its gain during the rental years can be taxable. The difference is structure and independent livability, not floor area.
My accountant suggested claiming CCA on the rental portion to save tax. Should I?
Price the cost first. Folio ¶2.60 is clear: the moment you claim CCA on the income-producing portion, the deemed disposition rule applies back to the day you started renting, piercing the principal residence exemption you were preserving. For an owner-occupier renting a room or two, the current-year depreciation rarely covers the extra tax at sale. Whether to claim CCA is a numbers-on-both-sides decision to run with your accountant.
I actually did convert the basement into a separate suite. Any way to avoid an immediate apportioned gain?
Since March 19, 2019, on a partial change in use you can elect under 45(2) so the deemed disposition that would otherwise arise does not apply (filed as a signed letter with your return for the year); a 45(3) election is available when an income portion is turned back to residential use. This option did not exist for partial changes before 2019. Eligibility and mechanics have conditions — leave that call to a licensed accountant.
Does Ontario add its own provincial rule I need to worry about?
No. Capital gains tax and the principal residence exemption are set by the federal Income Tax Act and administered by the CRA; Ontario has no separate provincial principal residence rule stacked on top. A taxable capital gain (50% of which is included in income) flows into your Ontario personal income tax along with everything else, but there is no “Ontario principal residence exemption.”
Arthur Zhao
Real Estate Broker · FRI · ABR · SRS · PSA · MCNE · E-PRO · CLHMS & GUILD Elite · REAIS
VP & Branch Manager, Bay Street Group Inc.
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