How to Change a Tax Return After Filing
Found a mistake after filing? How to change your return with Change my return, ReFILE or T1-ADJ, and how long it takes.
The short version
- Found a mistake after filing? Don't file a second return. Change the one you sent.
- Wait for your notice of assessment first, then use “Change my return” in CRA My Account, ReFILE in your tax software, or form T1-ADJ by mail.
- CRA's 2026 goal: about 2 weeks for routine online changes, 8 weeks by mail, longer if the request needs review.
- Refunds from a change are generally limited to the last ten calendar years.
- Some changes can't be made online, such as loss carrybacks, certain elections and bankruptcy returns.
How to Change Your Tax Return After You File
Everyone does it. You file in March, feel good about it, and then in May a donation receipt falls out of a drawer. The fix is simple and doesn't involve sending CRA a second return, which is the one thing that makes a small problem a messy one.
Step 1: Wait for the Notice of Assessment
CRA won't process a change until the original return has been assessed. Once your notice of assessment arrives, about two weeks after filing online, you're clear to go.
Step 2: Pick the Method
| Method | How | CRA's 2026 goal |
|---|---|---|
| Change my return | CRA My Account: pick the year and the line, enter the new amount | About 2 weeks for routine changes |
| ReFILE | Through the certified software you filed with: edit the return and send the change | About 2 weeks for routine changes |
| Form T1-ADJ | Paper form with an explanation and supporting documents, mailed to your tax centre | About 8 weeks for routine changes |
Requests that need a closer look can take much longer; CRA's standard for complex adjustments is 20 weeks. The progress tracker in My Account shows the expected date. Online, you usually only send receipts if CRA asks for them.
What You Can Change
- Income you forgot: a late T4, a T4A, a T5, a sale.
- Deductions and credits you missed: donations, medical expenses, moving costs, child care, union dues, tuition. Our guides to Canadian tax credits and deductions list what's claimable.
- Typos and amounts entered in the wrong box.
- Prior years, generally back ten calendar years for a refund.
What Can't Be Changed Online
“Change my return” and ReFILE don't handle a bankruptcy return (or any year before the bankruptcy), certain elections, or carrybacks of a loss, such as a capital or non-capital loss. Change my return also doesn't go back to 2015 or earlier. Those go on paper with form T1-ADJ or the specific form required, such as T1A for loss carrybacks.
Not sure the change is worth making?
Tell the assistant what you missed and the amount. It works out roughly what the change is worth at your marginal rate, and which line and method to use.
Change or Objection?
Two different tools:
- A change request is for mistakes or missed claims on your side. No deadline except the ten-year refund limit.
- An objection is for when CRA changed your return and you think CRA is wrong. It has a deadline: the later of 90 days after the notice or one year after the filing due date. A change request doesn't stop that clock. See notice of reassessment: what to do.
When a deadline is close and you're not sure which applies, file the objection. It protects your rights; a change request doesn't.
Disagree with CRA? File the objection properly
The Objection Pack reads your notice, works out your deadline, drafts your statement of facts and fills in form T400A for you to sign.
Fixing Mistakes That Mean You Owe
Correct it anyway. Interest runs from April 30 of the year after the tax year whether you fix it or CRA does. Fixing it yourself avoids the repeated failure to report income penalty that can apply when CRA finds it. If the problem is bigger, such as several years of unreported income, a voluntary disclosure before CRA contacts you may reduce penalties. See CRA tax problems, and get professional advice first.
Five Rules for Changing a Return
- Never file a second return for the same year.
- Wait for the notice of assessment before you send a change.
- Change only the lines that changed. The rest of the return stands.
- Keep the receipts in case CRA asks, even though online changes usually go through without them.
- Don't use a change request to fight CRA. That's an objection, with a deadline.
Best of all, catch it before you file: Return Check compares your slips with your return and flags missed claims, so there's nothing to change later.
Changing a Return: Questions
How do I change my tax return after filing in Canada?
Wait for your notice of assessment, then use Change my return in CRA My Account, ReFILE through certified tax software, or mail form T1-ADJ with supporting documents. Do not file a second return.
How long does it take CRA to process a change to my return?
CRA's 2026 goal is about two weeks for routine requests made online and eight weeks for requests by mail. Requests that need review can take much longer.
How many years back can I change my tax return?
You can ask for changes to prior years, but CRA generally will not issue a refund for an adjustment beyond ten calendar years.
Can I change my return before I get my notice of assessment?
No. CRA asks you to wait until you receive the notice of assessment for that return before requesting a change.
What changes cannot be made online?
Change my return and ReFILE cannot be used for bankruptcy returns, certain elections, or carrybacks of capital or non-capital losses. Those are made on paper.
Sources: CRA, Changing a tax return; Making changes to your tax return? Here's what's new (2026); Service Standards 2026-27. Checked October 2026.
Last reviewed October 4, 2026 against CRA and Government of Canada sources. How we check our facts.