Running a business from home: what it does to the principal residence exemption

For most Canadian business owners, the family home is the largest tax-sheltered asset they will ever own. So the question of whether working from it puts that shelter at risk is a fair one to ask — and the honest answer is that it usually does not, provided three conditions hold. It is worth knowing what they are, because one of them is a deduction plenty of owners claim without thinking.

What the exemption actually is

When you sell a home that was your principal residence for every year you owned it, the gain is generally not taxed. A property qualifies as your principal residence for a year if it is a housing unit (a house, condominium, apartment, cottage, mobile home or houseboat), you own it alone or jointly, you or your spouse or common-law partner or one of your children lived in it at some point during the year, and you designate it as your principal residence for that year.

Two limits are worth noting. Only one property per family per year can be designated for 1982 and later years. And the land counted as part of the principal residence is generally limited to half a hectare (1.24 acres), unless you can show more was needed for the use and enjoyment of the home — for example where a municipal minimum lot size was larger.

Even where the whole gain is exempt, the sale must still be reported: on Schedule 3 and Form T2091(IND) for the year of disposition.

The three conditions that protect the exemption

Where you start using part of your principal residence for rental or business purposes, the CRA usually considers you to have changed the use of that part — a partial change in use, with a deemed disposition of that portion. It does not apply that treatment if all three of the following are true:

• the rental or business use of the property is relatively small in relation to its use as your principal residence;
• you make no structural changes to the property to make it more suitable for rental or business purposes; and
• you deduct no capital cost allowance on the part used for rental or business.

Meet all three and the ordinary home office of an owner-managed business is a non-event for principal residence purposes. Fail any one of them and there is generally a deemed disposition of the affected portion, with proceeds and reacquisition cost equal to its proportionate share of fair market value at that time.

The CCA trap

Of the three, capital cost allowance is the one owners walk into. It is tempting: a home office is a genuine business space, the building is depreciable, and software will happily calculate the claim. The deduction is usually modest. The cost is that the business portion of the home stops being sheltered, and a share of every future dollar of appreciation becomes taxable.

On a home held for decades in a rising market, that trade is almost never worth making. It is why experienced advisers keep home-office claims to operating costs and leave the building alone — the same conclusion our guides to the home office deduction for incorporated owners and home office expenses reach from the deduction side.

Since 2019, an election is available

Before 19 March 2019 there was no way to elect out of the deemed disposition arising on a partial change in use. From that date onward, depending on the circumstances, an election under subsection 45(2) or 45(3) can be made so that the deemed disposition on a partial change in use does not apply. Where a deemed disposition does occur, a principal residence designation can still be made for the affected portion in the year of the change, by completing Part 2 of Schedule 3 and page 2 of Form T2091(IND). The mechanics of both elections are set out in our guide to change in use rules.

What happens on the eventual sale

If a portion of the home did change use, the sale is handled in parts:

• Split the selling price between the principal residence part and the rental or business part. The CRA will accept a split based on square metres or number of rooms, provided it is reasonable.
• Report the capital gain on the rental or business portion.
• Claim the principal residence exemption on the portion that never changed use, via Schedule 3 and Form T2091(IND). No gain is reported on that part.

The practical requirement is documentation you almost certainly do not have unless you created it deliberately: the floor areas, the dates the use changed, and a fair market value at each change. Keep it with your permanent tax records, not with the year's receipts.

Renting part of the home is the higher-risk version

A basement suite is a larger and more visible use than a spare-bedroom office, more likely to involve structural changes, and more likely to tempt a CCA claim. The same three conditions apply, but they are much easier to fail. If you are renting part of a home you live in, treat the change in use analysis as a live question rather than a formality, and split expenses between the personal and rented parts on a reasonable basis before claiming anything.

The bottom line

A home office does not usually cost you the principal residence exemption. Keep the business use modest relative to the home, avoid structural alterations made specifically for the business, and do not claim capital cost allowance on the building. Where the use is larger or a suite is involved, get the position confirmed before the deduction is claimed rather than in the year of sale — an accountant in Abbotsford can settle it in one conversation, and it protects a number that will matter far more later.

This article is general information for Canadian business owners and is current as of July 2026. It is not tax, legal or accounting advice, and your situation is unique — please speak with a CPA before acting on anything here.

Working through this locally? We advise owners on it as an accountant in Abbotsford.