Tax-loss harvesting is the practice of selling an investment that has declined in value to realize a capital loss. You then use that capital loss to offset capital gains you've already realized — reducing or eliminating the tax you owe on those gains. It sounds simple, and in principle it is. The catch is the superficial loss rule, which is Canada's version of the US "wash sale rule."
Done right, tax-loss harvesting is one of the few ways to legitimately reduce your tax bill in a non-registered account without fundamentally changing your investment strategy. Done wrong, the superficial loss rule disallows the loss entirely.
How Capital Gains Tax Works in Canada
Only capital gains realized in non-registered (taxable) accounts are relevant here. RRSP, TFSA, and FHSA are all tax-sheltered — gains and losses inside them have no tax consequence.
In Canada, capital gains are included in income at the inclusion rate. As of 2026, the inclusion rate is 50% for individuals on the first $250,000 of annual capital gains (and 66.7% above that threshold — the 2024 budget change). So if you sell a stock for a $10,000 gain, $5,000 of that gets added to your taxable income. At a 46.4% marginal rate (Ontario, ~$130,000 income bracket), you'd owe about $2,320 in tax on that gain.
Capital losses work symmetrically: a $10,000 capital loss reduces your taxable capital gains by $10,000. Net capital losses can be:
- Applied against capital gains in the current year
- Carried back 3 years to offset gains in prior years
- Carried forward indefinitely to offset future gains
The Superficial Loss Rule: Canada's 30-Day Rule
The CRA's superficial loss rule (ITA Section 54) says: if you sell a security at a loss and you (or an "affiliated person") buy the same or identical security within 30 days before or after the sale, the capital loss is disallowed. You can't claim it.
The 30-day window runs both directions — 30 days before the sale and 30 days after. So the total blackout window is 61 days (30 before + sale day + 30 after).
Who counts as an "affiliated person"? Your spouse or common-law partner. Corporations you control. Trusts you're a majority beneficiary of. If your spouse buys the same stock you just sold at a loss within 30 days, the loss is superficial — even if it was your spouse's own account making the purchase.
It doesn't include your RRSP or TFSA for purposes of the superficial loss rule. But there's a specific trap: if you sell at a loss in a non-registered account and immediately buy the same security in your RRSP or TFSA, the loss is still disallowed AND the "cost" added to the registered account is $0 (the ACB reset disappears into the registered account).
What Happens to a Superficial Loss?
When a loss is deemed superficial, it's denied — you can't claim it. But it doesn't disappear forever. The denied loss gets added to the Adjusted Cost Base (ACB) of the repurchased security. You'll eventually recover it when you sell that security for real (without triggering another superficial loss).
The practical implication: if you want to harvest a loss, you either need to stay out of that security for 31+ days after selling, or switch to a sufficiently different security in the same space.
The Real Example: $10,000 Loss Offsets $10,000 Gain
Ontario investor, ~$130,000 income, marginal rate 46.4%
January: Sold Canadian bank stock for a $10,000 capital gain. Tax owing on this gain: $10,000 × 50% inclusion × 46.4% marginal rate = $2,320 in tax.
November: Holds a Canadian energy ETF down $10,000 from purchase price. Sells it to realize the $10,000 capital loss. Waits 31 days before buying back (or buys a different but similar energy ETF immediately).
Result: $10,000 gain − $10,000 loss = $0 net capital gains. Tax owed on those gains: $0.
That $2,320 stays invested and compounds. Over 20 years at 7%, it grows to ~$8,900. Tax-loss harvesting is genuinely valuable — but only if you don't trigger the superficial loss rule and only if the math works out (transaction costs, bid-ask spreads, and the time cost of being out of the market matter for small amounts).
The Substitute Security Strategy
The cleanest way to harvest a loss without disrupting your asset allocation is to sell the losing investment and immediately buy a similar but not identical security. This keeps your market exposure intact while locking in the loss.
Common substitution pairs used by Canadian investors:
- XIU → XIC: Both track Canadian equities. XIU is the iShares S&P/TSX 60 ETF; XIC is the iShares Core S&P/TSX Capped Composite. Similar exposure, not identical securities.
- XEQT → VEQT: Both are all-equity asset allocation ETFs. Different providers, slightly different underlying weights.
- ZCN → VCN: BMO vs Vanguard Canadian equity index ETFs.
- Canadian bank stock → Canadian bank ETF (ZEB): Swapping an individual bank holding for the BMO Equal Weight Banks ETF maintains sector exposure.
Whether two securities are "identical" for superficial loss purposes is a grey area for ETFs tracking different but similar indexes. Most tax professionals consider ETFs tracking different indexes to be non-identical, but this isn't black-and-white. When in doubt, wait the 31 days.
When Does Tax-Loss Harvesting Make Sense?
Best time of year: November and December
Most tax-loss harvesting happens in Q4 — specifically November, with the deadline being a sale that settles by December 31. In Canada, the standard settlement for equities is T+1 (trade date plus one business day), so you can sell as late as December 30 and have the loss settle in the tax year. Check your broker's specific settlement schedule, as it can vary around the Christmas holiday.
Good candidates for harvesting
- Positions down 10%+ from your ACB with no fundamental change in your view of the holding
- Situations where you have a realized capital gain elsewhere in the year you want to shelter
- Securities where a good substitute exists, so you can stay invested
- Large unrealized losses ($5,000+) where the tax saving meaningfully exceeds transaction costs
When NOT to harvest losses
Small amounts: If the position is down only $500–$1,000, the tax saving is $115–$232. Two round-trip trades at $4.99/each at Questrade is already 4% of your tax saving. Factor in the bid-ask spread and potential slippage on thinly-traded securities.
You're in a low tax bracket: If your marginal rate on capital gains is only 15–20%, the math is less compelling. The benefit grows with income.
No gains to offset: If you have no capital gains this year or in the prior 3 years, a harvested loss just carries forward. It's still valuable, but less urgent.
You'll trigger superficial loss: If you can't stay out of the security for 31 days and have no suitable substitute, don't bother — the loss will be denied.
ACB Tracking Is Non-Negotiable
Tax-loss harvesting only works if you know your Adjusted Cost Base (ACB) — your actual cost per share including reinvested distributions and adjustments. CRA requires you to calculate and report capital gains/losses based on ACB. Brokerages show book value, but this can differ from CRA's ACB calculation (especially after receiving return of capital distributions or doing DRIP contributions).
For ETFs, the ACB gets complicated quickly: reinvested distributions, return of capital adjustments from T3 slips, and adjustments for fund mergers all affect it. The tool AdjustedCostBase.ca is free and widely used by Canadian investors to track ACB accurately.
See the mutual fund tax guide and the T3 and T5 slip guide for how to handle the annual distributions that affect your ACB calculations.
RRSP and TFSA: Cannot Be Used for Capital Losses
This is one of the most common misconceptions. Capital losses inside an RRSP or TFSA are completely irrelevant for tax purposes — they can't be claimed, carried back, or carried forward. Selling a losing ETF inside your TFSA does nothing for your tax bill. The only place tax-loss harvesting works is in a non-registered (taxable) account.
This is also why asset location matters. Ideally, you hold your most volatile assets (where losses might occur that you'd want to harvest) in non-registered accounts, and use RRSP/TFSA for bonds and US equities (where tax efficiency comes from sheltering the interest income or US withholding tax).
For the full picture on which assets go where, see the non-registered account investing guide and the guide on foreign withholding tax in RRSP vs TFSA.
The Superficial Loss + RRSP Trap (Important)
There's a specific scenario that catches investors off-guard. If you:
- Sell a security at a loss in your non-registered account
- And buy the same security in your RRSP or TFSA within the 30-day window
The capital loss is denied as a superficial loss. But here's the extra sting: the denied loss can't be added back to the ACB of the registered account holding (since there's no ACB inside an RRSP/TFSA). The loss is gone permanently — it doesn't carry forward at all.
The fix is simple: wait 31+ days before buying the same security inside a registered account, or buy it inside the registered account first (before selling at a loss in the non-reg), since the superficial loss rule only looks 30 days after the sale, not 31+ days prior.
Carrying Losses: Backward 3 Years, Forward Indefinitely
If you have no capital gains this year to shelter, harvested losses are still worth taking. You can:
- Carry back 3 years: Apply the loss against capital gains from 2023, 2024, or 2025 and get a refund. File a T1A form (Request for Loss Carryback) with your tax return.
- Carry forward indefinitely: The loss sits on your CRA My Account record and automatically offsets future capital gains — useful for investors who expect large gains when eventually selling a cottage, investment property, or concentrated stock position.
This makes December harvesting valuable even in a year with no gains: you're building a forward-loss balance. When you eventually sell your rental property and trigger a large capital gain, those accumulated losses will be there.
Connecting to the Capital Gains Inclusion Rate Change
The 2024 federal budget proposed increasing the capital gains inclusion rate from 50% to 66.7% for gains above $250,000 annually (for individuals). This makes tax-loss harvesting more valuable for investors with large gains, since the tax saved per dollar of loss is higher at the 66.7% inclusion rate. A $10,000 loss at 66.7% inclusion and 46.4% marginal rate saves $3,087 — versus $2,320 at 50% inclusion.
See the capital gains inclusion rate guide for the full details on how the two-tier system works.
Should You Automate It?
Some robo-advisors (Wealthsimple, Justwealth, and others) offer automatic tax-loss harvesting as a feature for non-registered accounts. They monitor daily price movements and automatically trigger harvests when losses hit a threshold. This is genuinely useful for set-it-and-forget-it investors who wouldn't otherwise review their non-reg portfolio quarterly.
The limitation: automated harvesting only works within the ETF universe the robo-advisor offers. If you hold individual stocks or ETFs outside their platform, they can't see or manage those. The robo-advisor comparison covers which platforms offer tax-loss harvesting and how their implementations differ.