Capital cost allowance is the only deduction on Form T776 with a bill attached to it.

Everything else on the form reduces your tax and ends there. Capital cost allowance reduces your tax now and hands part of it back to the CRA the year you sell. Used well, it is a deferral worth thousands. Used without thinking, it turns a tax-free principal residence sale into a taxable one.

Here is how it works for a Canadian landlord with a handful of doors.

The basic mechanic

You do not deduct the cost of a building in the year you buy it. You deduct a percentage of the declining balance each year. The deduction is capital cost allowance, entered on line 9936 of Form T776.

Land is never depreciable. Your first job on any purchase is splitting the price between land and building, usually using the municipal assessment ratio. Get the split documented at purchase, because reconstructing it eight years later is guesswork.

The classes landlords use

• Class 1 at 4% — most residential rental buildings acquired after 1987. Includes the structural components: wiring, plumbing, heating, air conditioning, lighting, sprinklers.
• Class 3 at 5% — buildings acquired before 1988. Post-1987 additions to a Class 3 building stay in Class 3 up to the lesser of $500,000 or 25% of the building's capital cost. Anything past this goes to Class 1.
• Class 6 at 10% — frame, log, stucco-on-frame, galvanized iron or corrugated metal buildings acquired before 1979, or buildings with no footings below ground level.
• Class 8 at 20% — the class most small landlords touch most often. Appliances, furniture, window coverings, tools costing $500 or more, equipment.
• Class 50 at 55% — computer hardware and systems software.
• Class 1 at 10% for purpose-built rental housing — a Budget 2024 measure. It applies to new purpose-built rental with at least four private apartment units, or at least ten private rooms or suites, where at least 90% of units are held for long-term rental. Construction must have begun on or after April 16, 2024 and before January 1, 2031, with the property available for use before 2036. New builds and conversions of non-residential buildings qualify; renovating an existing residential building does not. Most landlords with a few doors won't touch this one, but anyone building a fourplex should ask their accountant about it directly.

One clarification worth making, because it circulates wrongly on landlord forums: the 6% and 10% enhanced rates for non-residential and manufacturing buildings do not apply to residential rentals. Don't claim them on a duplex.

Four rules governing the claim

• The half-year rule — in the year you acquire an asset, you claim capital cost allowance on half the addition. Newer acquisition incentives have changed this for some property acquired from January 1, 2025 onward under the federal government's reaccelerated investment incentive, which restores a higher first-year deduction. The rules are new and the eligibility details matter, so treat this as a question for your accountant rather than a setting in your spreadsheet.
• Capital cost allowance never creates or increases a rental loss — you claim up to the point where net rental income hits zero, and no further. The test is applied across your whole portfolio, not property by property. A profitable duplex absorbs capital cost allowance while a vacant condo runs at a loss, as long as the total stays at or above zero.
• Separate class for buildings costing $50,000 or more — each rental building acquired after 1971 costing $50,000 or more sits in its own class rather than pooling with your other buildings. This is not optional. It matters on sale, because a building alone in its class produces a clean terminal loss where the remaining undepreciated capital cost exceeds the proceeds.
• You choose the amount every year — capital cost allowance is discretionary. Claim the full amount, a partial amount, or nothing. Unclaimed room carries forward. This flexibility is the actual planning tool.

What happens when you sell

Two outcomes, both on Form T776.

Recapture, line 9947 — where the proceeds allocated to the building exceed the remaining undepreciated capital cost, the difference comes back into income, capped at the total capital cost allowance you claimed. Recapture is fully taxable at your marginal rate. It is not a capital gain, so the 50% inclusion rate does not soften it.

Canadian real estate appreciates more often than it depreciates, so recapture is the normal outcome, not the exception. Every dollar you claimed at a 40% marginal rate comes back at whatever your marginal rate is in the year of sale, which for many landlords is higher because the sale year includes a capital gain.

Terminal loss, line 9948 — the reverse. Undepreciated capital cost exceeds proceeds, and you deduct the difference in full. Rarer for buildings, common for appliances and furniture.

The trap involving your own home

This one costs the most and gets discovered too late.

Claim capital cost allowance on a property, and you lose the ability to designate the property as your principal residence for any year you claimed it.

It runs further. If you moved out of your home and rented it, and filed a subsection 45(2) election so it stays your principal residence for up to four more years, claiming capital cost allowance rescinds the election. The same applies in reverse — subsection 45(4) nullifies a 45(3) election where capital cost allowance was allowed on the property for any period after 1984.

So a homeowner renting out their old house, filing the election properly, then letting tax software auto-claim capital cost allowance because it lowered the balance owing by $600, has traded a tax-free gain for a taxable one. Software does this by default. Check the box.

When claiming makes sense

Claim it when the property is a long-term hold with no principal residence history, your current marginal rate is high, your rental income is positive, and you'd rather have the cash now.

Skip it when the property was or might become your principal residence, you plan to sell within a few years, your income this year is unusually low, or your rental income is already near zero.

The deferral is only worth what you do with the money. Capital cost allowance moves tax from this year into the sale year. If the deferred dollars sit in a chequing account, you've gained close to nothing and added complexity. If they go toward the next down payment, the math works.

What your books need to support it

Per property: the land and building split with the source document. Every capital addition by date, description and amount. The class assigned. Opening and closing undepreciated capital cost for each class each year. The cumulative capital cost allowance claimed.

The schedule follows the property until you sell it, and it's the first thing your accountant asks for in the year of the sale.

LuxOasisOS keeps a capital additions register per unit alongside the operating ledger, so the depreciation schedule and the cost base are built as you go rather than reconstructed at disposition.