Carrying a Net Capital Loss Back to Prior Years in Canada

You sold an investment for less than you paid, and in earlier years you paid tax on gains. It is natural to ask whether the loss can bring some of that tax back. In Canada, it sometimes can, but only within the rules for net capital losses.

This article explains what a net capital loss is, how the three-year carryback works, which form to use, and the exceptions that catch people out. Your own facts decide the result, so treat this as a guide to the questions to ask.

This article covers Canadian federal tax law, which applies in every province.

What a net capital loss is

Only half of a capital loss counts. The allowable capital loss for a year is one-half of the capital loss, just as the taxable capital gain is one-half of the gain. If your taxable capital gains for the year exceed your allowable capital losses, the difference is added to your income on line 12700.

If it goes the other way, you have a net capital loss. On Schedule 3, a negative result does not go to line 12700. That net capital loss is what you may be able to carry to another year.

The carryback and carryforward rules

Net capital losses can be applied only against taxable capital gains. They can be carried back three years and carried forward indefinitely. Losses from earlier years are applied oldest first, and the amount you apply is limited to the taxable capital gains in the year you apply it to.

For example, a 2025 net capital loss can go back to 2022, 2023 or 2024. Carrying it back reduces taxable income but does not change net income.

How to make the request

Use Part 5 of Form T1A, Request for Loss Carryback. You do not file an amended return for the earlier year.

• Confirm the loss on your Schedule 3 for the year it happened.
• Check which of the three earlier years had taxable capital gains.
• Complete Part 5 of Form T1A for the year you want to carry the loss back to.
• Keep your Schedule 3 workings and the earlier notices of assessment with your copy.

Because losses are applied oldest first, and only up to the taxable gains in the year they are applied, you may not be able to use the whole loss in one year. Any unused part is not lost; it can be carried forward.

Exceptions and traps

• Lifetime exemption: carrying a net capital loss back may reduce a capital gains deduction claimed in that year or later years.
• Business investment losses: an allowable business investment loss (ABIL) can be deducted against other income, not just capital gains. Any unused excess becomes a non-capital loss, carried back 3 years and forward 10, and an ABIL not used within 10 tax years becomes a net capital loss in the eleventh year.
• Superficial losses: a loss is superficial if you, or someone affiliated with you, acquires the same or identical property from 30 days before to 30 days after the sale and still owns it, or has a right to acquire it, at the end of that period. Affiliated persons include your spouse or common-law partner and a corporation you or your spouse control.
• A superficial loss cannot be deducted and is usually added to the cost base of the substituted property. Certain situations, such as the owner becoming a non-resident or the owner's death, are not treated as superficial losses.

The superficial loss rule matters because a loss you thought you had may not exist for tax purposes. Check it before you plan a carryback.

What to do next

• List every sale in the year, with proceeds, adjusted cost base and selling costs.
• Check for any repurchase of the same or identical property within 30 days before or after a loss sale.
• Pull your assessments for the three earlier years and see how much taxable capital gain each one had.
• Decide whether to carry the loss back or keep it for the future, keeping any lifetime exemption claims in mind.
• Have an accountant or lawyer review the T1A before you file if the numbers are large or an ABIL is involved.

Frequently asked questions