Capital Gains on a Cottage or Second Property in Ontario, Explained
Your principal home is sheltered when you sell it; a cottage or second property is not. What gets taxed, how the bill is actually calculated, and the designation choice — made year by year, at sale time — that decides which of your properties the principal residence exemption covers.
Why the cottage is different
When you sell the home you live in, Canadian tax law generally shelters the profit under the principal residence exemption. A cottage, a ski condo, or a second house in the city gets no such automatic shelter. It is a capital property, and when you sell it — or are treated as having sold it — the increase in value is a capital gain, and half of that gain is taxable.
That surprises owners because the cottage feels personal, and it is. But the tax system doesn't ask how a property feels; it asks which property you have designated as your principal residence, and there can only be one answer for each year. Everything else is exposed for the years it isn't designated.
This is general information about how the tax works, not tax advice — a cottage sale is worth an hour with an accountant before you list.
Which property gets the exemption
A family unit — you, your spouse or common-law partner, and your minor children — can designate only one property as a principal residence for any given year. You make the designation year by year, and you make it when you sell, looking back over the whole period of ownership and choosing which property the exemption serves best. Owners usually assume the house wins automatically. It doesn't. The designation is a choice, and on a property that has appreciated hard, it can be the most valuable form you ever sign.
A cottage can qualify. The test is that the property be "ordinarily inhabited" by you or your family in the year — and the tax authority accepts that even a short seasonal stay can meet that test, provided the property isn't mainly held to earn income. So the cottage years aren't automatically lost years. If the cottage has gained more than the house, designating the cottage for some or all of the overlapping years may shelter more — at the cost of leaving those years of the house's gain exposed when it eventually sells. The exemption is calculated with a formula that counts the years a property is designated, and it includes a "plus one" rule that effectively adds a year, which is why moving from one principal residence to another doesn't normally cost you.
How the gain is calculated
The arithmetic itself is plain. Start with the proceeds of sale. Subtract the adjusted cost base — the ACB — and the costs of selling. What remains is the capital gain. One half of it is added to your income in the year of sale: the proposed increase was dropped in 2025; the inclusion rate remains one-half.
The ACB is where sales are won and lost quietly. It begins with what you paid, plus the costs of buying — land transfer tax and legal fees among them, which are part of the same ledger as your other closing costs. It grows with capital improvements: a new roof, an addition, a rebuilt septic system — work that improves the property. Routine maintenance and repairs do not increase the ACB, which is why the line between an improvement and a repair matters and why receipts matter more.
A worked example
An example, with round numbers. You bought the cottage for $300,000. Over the years you added $60,000 of capital improvements, bringing the adjusted cost base to $360,000. You sell for $700,000, and the costs of selling — commissions and legal — come to $35,000, the kind of figures tallied in the cost of selling a home.
The gain is $700,000 minus $360,000 minus $35,000: $305,000. The taxable half is $152,500, added to your income in the year of the sale and taxed at your marginal rate — which means the actual tax bill depends on your other income that year and cannot be stated as a single number without knowing it. If you can designate the cottage as your principal residence for some of the years you owned it, the exempt portion of the gain comes off first, and only the remainder runs through this arithmetic.
Change-of-use traps
The gain doesn't always wait for a sale. When you change how a property is used — you start renting the cottage out, or you move into a house you had been renting — tax law generally treats you as having sold the property at fair market value and bought it back again. That deemed disposition can crystallize a gain you haven't seen a dollar of. Elections exist that can defer this in some circumstances, but they have conditions and deadlines, and missing them is easy if nobody tells you the change of use mattered. Tell your accountant before the use changes, not after.
What to keep
Keep the paper. The purchase agreement and closing statement, the land transfer tax and legal receipts, and an invoice for every capital improvement across the whole ownership — roof, addition, septic, dock rebuilt rather than repaired. Decades later, every dollar of ACB you can prove is a dollar of gain you are not taxed on, and the seller who kept a folder is in a different position from the seller reconstructing twenty years from memory. Valuations matter too: if a property became a cottage or a rental partway through, a valuation at the change date can anchor the numbers.
The bottom line
The cottage is taxed because only one property can be your principal residence for a year, and the choice of which one is yours to make — at sale time, with the whole picture in front of you. Get the gain arithmetic right, keep the ACB records, and take advice before you list. The natural first step is knowing what the property would sell for: start with what your home is worth, and bring that number to the conversation.
