What Every Canadian Homeowner Should Know Before Handing a Relative the Keys to the Basement
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There's something quietly wonderful about a secondary suite. The basement that used to collect old paint cans becomes a bright little apartment for your mom. The laneway house out back gives your adult son a first taste of independence without a punishing rent cheque. You get to keep family close, share the cost of a home, and put square footage to work all at once.
Then tax season arrives, and the warm glow gets complicated. Do you have to claim the money your daughter gives you each month? Can you write off a share of the mortgage and the hydro bill? And here's the one that keeps people up at night: could renting to family quietly cost you the tax-free status on the home you actually live in?
The good news is that the rules are more navigable than they look, and once you understand the handful of levers that matter, you can set things up in a way that keeps both you and the Canada Revenue Agency comfortable. This guide walks through what counts as rent versus cost sharing, how to protect your principal residence exemption, why claiming depreciation is usually a trap, and the one genuine tax break designed for exactly this situation. A quick note before we start: this is general information for Canadians, not personal tax advice, and the landlord, zoning, and licensing rules that also apply to a suite are set province by province and city by city, so treat those as a separate conversation.
Before you can figure out what to report, you need to know which of two worlds your arrangement lives in. The CRA draws a firm line between a genuine rental and a "cost-sharing arrangement," and where you land determines everything that follows.
The dividing line is the rent itself. When you charge a family member noticeably less than you would charge a stranger, the CRA generally treats the money as a contribution toward the household rather than rental income. As the CRA explains on its guidance for renting below fair market value, when someone living with you pays a small amount toward upkeep or groceries, you do not report that amount as income, you cannot claim rental expenses, and because it is a cost-sharing arrangement, you cannot claim a rental loss. In plain terms, a generous discount for your parent or your kid usually means the whole thing sits outside the tax system: no income in, no deductions out.
What trips people up is the hope for a middle path, where you give your relative a break on the rent but still write off a slice of the mortgage interest and utilities to create a handy loss. That door is closed. If you lose money because you rent to someone you know for less than you would charge someone you don't, you simply cannot claim that loss. You can only treat the arrangement as a real rental when you charge your relative the same rate you would charge any other tenant and you genuinely expect to turn a profit over time. Family members are what the tax world calls "non-arm's-length" or related persons, and that label is precisely why these rentals get a closer look than a lease with a stranger would.
Because the rent level is the hinge everything swings on, it's worth setting it with care. Fair market rent is simply what a comparable suite would command from an unrelated tenant in your area. You can arrive at a defensible number by looking at what similar basement or laneway units lease for nearby, and Canada's shifting rental market means those comparables move, so it pays to check current listings rather than rely on last year's figure. Keep a few screenshots or a short note explaining how you settled on the amount. If you ever need to show that you charged a market rate and expected a profit, that little paper trail does a lot of quiet work.
Before you can figure out what to report, you need to know which of two worlds your arrangement lives in. The CRA draws a firm line between a genuine rental and a "cost-sharing arrangement," and where you land determines everything that follows.
The dividing line is the rent itself. When you charge a family member noticeably less than you would charge a stranger, the CRA generally treats the money as a contribution toward the household rather than rental income. As the CRA explains on its guidance for renting below fair market value, when someone living with you pays a small amount toward upkeep or groceries, you do not report that amount as income, you cannot claim rental expenses, and because it is a cost-sharing arrangement, you cannot claim a rental loss. In plain terms, a generous discount for your parent or your kid usually means the whole thing sits outside the tax system: no income in, no deductions out.
What trips people up is the hope for a middle path, where you give your relative a break on the rent but still write off a slice of the mortgage interest and utilities to create a handy loss. That door is closed. If you lose money because you rent to someone you know for less than you would charge someone you don't, you simply cannot claim that loss. You can only treat the arrangement as a real rental when you charge your relative the same rate you would charge any other tenant and you genuinely expect to turn a profit over time. Family members are what the tax world calls "non-arm's-length" or related persons, and that label is precisely why these rentals get a closer look than a lease with a stranger would.
Because the rent level is the hinge everything swings on, it's worth setting it with care. Fair market rent is simply what a comparable suite would command from an unrelated tenant in your area. You can arrive at a defensible number by looking at what similar basement or laneway units lease for nearby, and Canada's shifting rental market means those comparables move, so it pays to check current listings rather than rely on last year's figure. Keep a few screenshots or a short note explaining how you settled on the amount. If you ever need to show that you charged a market rate and expected a profit, that little paper trail does a lot of quiet work.
Setting the rent at market value and charging it consistently is what unlocks your ability to deduct expenses. If you want to help a relative financially, it's often cleaner to charge full rent and then gift money back separately, rather than blur the two by discounting the rent itself.
Once you've established that you're running a genuine rental at a fair rate, the reporting side becomes refreshingly ordinary. You report your gross rent and your net rental income on your personal return, and you use Form T776, Statement of Real Estate Rentals, to lay out the income and expenses that get you there. For the deeper walkthrough with line-by-line examples, the CRA's plain-language companion is Guide T4036, Rental Income.
Because a suite occupies only part of your home, you deduct only the part of your household costs that reasonably belongs to the rental. The most common approach is to allocate shared costs, such as mortgage interest, property tax, insurance, heat, and electricity, based on the percentage of your home's floor area the suite takes up. If the basement apartment is a quarter of your square footage, claiming roughly a quarter of those shared bills is a sensible, well-accepted starting point. Costs that belong entirely to the rental, like a repair inside the suite itself, are fully deductible, while anything purely personal stays off the form. This is the same logic that runs through what Canadian homeowners can and can't write off, just applied to the four walls you rent out.
Here's a simple way to see how the two worlds diverge in practice.
This is the worry that matters most, because it touches the single biggest tax break most Canadians ever get: the principal residence exemption, which can erase the capital gain on your home when you sell it. The reassuring news is that renting out part of your home does not automatically put that exemption at risk.
The CRA has a long-standing administrative practice, set out in its Income Tax Folio on the principal residence, of treating your entire property as remaining your principal residence when three conditions are all met: the income-producing use is ancillary to the main use of the home as your residence, there is no structural change to the property, and you claim no capital cost allowance on it. The folio even names renting out one or more rooms as a classic example of an arrangement that clears this bar. In that situation you still report the rent and deduct a reasonable portion of your expenses, but the home keeps its full exemption.
So a parent living in a spare bedroom and sharing your kitchen, or an adult child in a finished basement that hasn't been walled off into its own dwelling, generally keeps you on the safe side of that line. The rental is a supporting act, not the main event, and nothing about the building has fundamentally changed.
The three conditions work as a set, not a menu. Break any one of them, and the protection can fall away. The condition homeowners most often stumble over on their own is the last one, capital cost allowance, which is why it deserves a section of its own.
Capital cost allowance, or CCA, is the tax term for depreciation. It lets you deduct a portion of a building's cost each year against the income it earns. On a pure investment property that can be a useful tool, and claiming it on your home's rented portion is entirely optional. For a family suite inside your principal residence, though, reaching for it usually backfires in two ways.
First, it can quietly undo the very protection we just described. The principal residence folio is explicit that if you start claiming CCA on the income-producing portion, the deemed disposition rules apply as of the moment the rental use began, which pulls the rug out from under that safe-harbour treatment. Second, whatever depreciation you claim over the years comes back to find you when you sell. That claimed CCA is "recaptured," meaning it gets added back into your income in the year of sale as fully taxable income, rather than being sheltered as a lower-taxed capital gain. You get a modest deduction today and a larger, less favourable bill later.
For most families with a modest suite, the cleaner path is simply not to claim CCA at all. You give up a small annual deduction, and in exchange you keep your home's exemption intact and sidestep a nasty surprise down the road. If your situation is larger or more commercial in scale, that trade-off deserves a real conversation with your accountant, but as a default, leaving depreciation alone is the friendlier choice.
There's a meaningful difference, in the CRA's eyes, between renting out a room and building a fully self-contained unit. Once a space has its own entrance, kitchen, and bathroom, it starts to look less like part of your house and more like a separate dwelling, and that's where the tax picture shifts.
The principal residence folio describes a deemed disposition applying when a change in use is "substantial and of a more permanent nature," involving a structural change, and it specifically names converting part of a house into a self-contained domestic establishment for earning rental income as an example. In practical terms, carving your basement into a true legal apartment can trigger a partial change in use. When that happens, the tax rules treat you as having sold the rented portion at its fair market value and immediately reacquired it, with the principal residence exemption usually covering any gain up to that point, but with future growth on the rental portion potentially becoming taxable when you eventually sell. If you're weighing whether to build to that standard, it's worth understanding both the permit side of a renovation and this tax side together, since the structural choices drive both.
Happily, there's a designed escape hatch. You can elect under subsection 45(2) of the Income Tax Act to be treated as not having made that change in use, which defers recognizing any gain. This election used to be off-limits for partial changes, but since March 19, 2019, it has been available when only part of a property changes use, which is exactly the secondary-suite scenario. You make it by filing a signed letter with your tax return for the year the change happened, and it comes with one firm string attached: you can't claim CCA while it's in force, or the election is treated as rescinded. Used well, it can even let the property qualify as your principal residence for up to four additional years. Because this is a genuine election with real consequences, it's the natural moment to loop in a tax professional who can file it correctly for your year.
When you do sell, the principal residence exemption is calculated with a formula that rewards the years your home genuinely served as your residence. The folio expresses it as A multiplied by B divided by C, where A is the gain, B is one plus the number of years the home was your principal residence while you were a Canadian resident, and C is the number of years you owned it. That "one plus" is a small kindness in the rules that generally helps cover the year you buy and the year you sell.
For a suite that stayed within the safe harbour, this math typically shelters your whole gain, because the property never lost its character as your residence. Where a portion was treated as converted to rental use, the exemption may cover most of the gain but carve out the part attributable to the rental portion during its rental years. Any taxable capital gain that does arise is currently taxed at the one-half inclusion rate, meaning half the gain is included in your income, as the Department of Finance confirms in its capital gains inclusion rate backgrounder. You may recall headlines about that rate rising to two-thirds; that proposed increase was cancelled and never became law, so the familiar one-half rate is what applies.
It's easy to focus on the traps, so let's end the tax-rules portion on a genuinely encouraging note. If you're renovating to create a suite so that an aging parent or a disabled adult relative can live with you, the federal government offers a credit designed for precisely that. The Multigenerational Home Renovation Tax Credit is a refundable credit worth 14.5% of up to $50,000 in eligible renovation costs, for a maximum of $7,250, and because it's refundable, you can receive it even if you owe no tax.
To qualify, the renovation has to create a self-contained secondary unit, complete with its own entrance, bedroom, bathroom, and kitchen, so a qualifying individual can live with a qualifying relation. The qualifying individual is either a senior who is 65 or older by the end of the renovation year, or an adult who is eligible for the disability tax credit. The family net is cast wide, covering parents, grandparents, children, grandchildren, siblings, and more. You claim it on line 45355 of your return, supported by Schedule 12. It's a rare case where the tax system and a warm family decision point in exactly the same direction.
Notice the tension worth planning around: the very features that qualify a suite for this credit, its own entrance and kitchen, are also the features that can trigger a change in use for your principal residence. That's not a reason to avoid the credit; it's a reason to plan the whole picture, ideally the election included, with a professional.
For most family suites, sales tax is a non-issue, and it's worth saying so plainly to put the worry to rest. Long-term residential rentals, meaning leases of one month or more, are exempt supplies under the rules the CRA sets out for residential real property rentals, so you do not charge GST or HST on the monthly rent you collect from your relative. The one place complexity can creep in is when you build or substantially renovate to create a brand-new unit, where self-supply rules and possible rebates can come into play. That's a narrow, project-specific situation, and it's the right time to get tailored advice rather than guess.
If you take one practical habit from all of this, let it be good record-keeping paired with a few deliberate choices at the start. A little organization now prevents almost every headache later.
Renting your secondary suite to family doesn't have to be a tax minefield. It's really a few clear decisions, made on purpose, that let you keep helping the people you love while protecting the home you've worked hard for. Handle the rent honestly, leave depreciation alone, and know where the credit and the election fit, and you'll have the confidence to enjoy the arrangement for what it is.
About the Author
Angela Nightingale is the Senior Editor at Homeowner.ca with two decades of experience in digital publishing and content strategy. She has owned two homes, taken on her share of DIY projects, and learned what most guides fail to mention. She writes from the belief that the best home guidance comes from people who have lived through the decisions — and her goal is always to leave readers feeling confident, not overwhelmed.
It depends on the rate. If you charge a relative below-market rent as a contribution to the household, the CRA generally treats it as cost sharing, and you neither report the money nor deduct expenses. If you charge full market rent and expect a profit, it's a genuine rental that you report on Form T776.
It's when someone living with you pays a modest amount toward upkeep or groceries rather than a true market rent. The CRA treats this as sharing costs, not earning income, so there's nothing to report and nothing to deduct, and you cannot claim a rental loss.
No. There's no middle option. If you rent below market to someone you know and lose money, you cannot claim that loss. To deduct expenses, you need to charge the same rate you'd charge any tenant and genuinely expect a profit.
Not if you stay inside the CRA's safe harbour: the rental use is ancillary to living there, you make no structural changes, and you claim no capital cost allowance. Meet all three and your home generally keeps its full exemption.
It's depreciation on the building, claimed against rental income. On a family suite it usually backfires, because it can trigger a change in use that undermines your exemption, and any amount claimed is recaptured as fully taxable income when you sell.
A fully self-contained unit can count as a structural change, which may trigger a partial change in use and a deemed disposition of the rented portion. A subsection 45(2) election can defer the tax hit, provided you don't claim CCA.
Yes. The Multigenerational Home Renovation Tax Credit gives you 14.5% of up to $50,000 in eligible costs, to a maximum of $7,250, when you build a self-contained unit so a senior or a disability-tax-credit-eligible adult relative can live with you.
For long-term residential rent of one month or more, no. Those rentals are exempt supplies, so you don't add sales tax to the rent. Building a brand-new unit can raise separate GST/HST questions worth reviewing with a professional.
For a simple room rented at market rate with no CCA, many people manage on their own using CRA guidance. Once you're building a self-contained suite, considering the 45(2) election, or claiming the renovation credit, a tax professional is well worth it.
