Ontario business owners can use non-capital losses and capital losses to recover tax already paid or reduce tax in future years. The rules are set by the Canada Revenue Agency (CRA) and apply to both sole proprietors (T1) and corporations (T2). This guide explains the current carryback and carryforward periods, how to apply the losses correctly, and the mistakes that cause business owners to lose the benefit.
Non-capital loss rules
A non-capital loss generally occurs when allowable expenses from a business or property exceed income from those sources in a taxation year.
- Carryback period: 3 years
- Carryforward period: 20 years (for losses arising after 2005)
- What it offsets: Taxable income from any source (with certain restrictions)
- How to claim a carryback: File Form T1A (personal) or the equivalent corporate schedule within the required time limit
- Result of a successful carryback: Refund of tax previously paid in the prior years
Capital loss rules
A capital loss arises when capital property (shares, investment real estate, etc.) is sold for less than its adjusted cost base (ACB).
- Carryback period: 3 years
- Carryforward period: Indefinite
- What it offsets: Taxable capital gains only (not regular income)
- Inclusion rate: 50% (same as capital gains)
- How to claim a carryback: Request the carryback on the return for the year the loss occurred
Selling real estate at a gain or a loss? Read Selling a Rental Property in Ontario? Here’s How Capital Gains Tax Works.
Quick comparison
| Loss type | Carryback | Carryforward | Can offset |
|---|---|---|---|
| Non-capital loss | 3 years | 20 years | Most types of income |
| Net capital loss | 3 years | Indefinite | Taxable capital gains only |
Common mistakes that reduce the value of losses
- Missing the three-year carryback deadline so prior-year tax cannot be recovered
- Applying a non-capital loss against capital gains (or a capital loss against regular income)
- Failing to track adjusted cost base correctly, which changes the amount of the loss
- Losing loss balance records when changing accountants or self-filing for multiple years
- Not coordinating loss application with other corporate tax accounts (such as NERDTOH or ERDTOH)
These errors often show up alongside others — see Common Self-Filing Mistakes Ontario Business Owners Make (And How They Cost You).
Steps to use losses effectively
- Calculate the loss correctly in the year it arises and report it on the T1 or T2.
- Decide whether a carryback will produce a refund and file the required form on time.
- Maintain a running schedule of unused loss balances by year and type.
- Apply losses in future years against the correct type of income and in the proper order.
- Keep supporting documentation (ACB calculations, sale agreements, expense records) in case of CRA review.
Timing matters for corporations — see Corporate Tax Filing Deadlines & Penalties in Ontario.
Frequently asked questions
Can I carry a business loss back to get a refund?
Yes. A non-capital loss can be carried back three years. If you had taxable income and paid tax in those years, the carryback can generate a refund.
Do capital losses expire?
Net capital losses can be carried forward indefinitely, but they can only offset taxable capital gains.
What happens if I forget to apply a loss?
Unused non-capital losses expire after 20 years. Capital losses do not expire but remain unavailable until you have capital gains to offset.
Does Ontario have different rules?
The carryback and carryforward periods follow the federal Income Tax Act. Ontario tax is affected because the loss reduces taxable income used for both federal and provincial calculations.
How Chrome Accounting helps Ontario business owners
Chrome Accounting reviews prior-year T1 and T2 returns, calculates available non-capital and capital loss balances, and applies them in the most tax-efficient way. We help Ontario business owners recover tax through carrybacks and reduce future tax through proper carryforwards. Learn more about our corporate tax filing and personal tax for business owners services, or meet the founder, Ali Alsharif, CPA.
Have unused losses on your books?
Ali Alsharif, CPA, MPAcc — Chrome Accounting. Fully virtual, serving all of Ontario — no office visit required. If you have unused losses or want to confirm your balances are being applied correctly, contact us for a review.
T: +1 289 969 3491 · cpa@chromeaccounting.ca · Connect on LinkedIn
Contact UsDisclaimer: This article provides general information only and is not tax, legal, or accounting advice. Loss carryback and carryforward rules contain specific conditions and can change. Results depend on individual circumstances. Consult a qualified CPA before taking any action. Chrome Accounting is not responsible for decisions made based on this content.