# Changing your return, and disputing an assessment

> Reading your notice of assessment, fixing a mistake with Change my return, ReFILE or Form T1-ADJ, how far back you can go, and how to object.

- Web page: https://taxnotes.ca/guides/changing-your-return/
- For: Individuals & families · Topic: Filing your return
- Last reviewed: 2026-10-11

After you file, the CRA sends a notice of assessment. If you then spot a mistake or something you forgot to claim, you ask the CRA to change the return. If the CRA changed something and you think it got it wrong, you can file a formal objection. The two routes are different, and picking the right one saves time.

## Your notice of assessment

The notice of assessment is the CRA's summary of your return as it processed it. If the CRA later changes an assessed return, it sends a notice of reassessment showing the changes.

You'll find it in your CRA account once your return is processed, usually right away. The CRA sends it as online mail (with an email alert if you've given it your email address) unless you've chosen letter mail or never provided an email address.

What to check:

- **Account summary:** "Refund", "Amount due" or "Balance: Nil".
- **Assessment summary:** the main amounts the CRA used. Compare them with what you entered to see whether anything was changed.
- **Explanation of changes:** if the CRA corrected your return, it says what and why.
- **Plan statements:** where they apply, your RRSP deduction limit, Home Buyers' Plan or Lifelong Learning Plan repayments, and FHSA participation room for next year.

Keep it. It also has the access code you can use to file online next year.

## Fixing a mistake: ask for a change

You can ask the CRA to change a return to report income you left out (a T4 slip or tips, say), claim a deduction or credit you missed (such as child care or medical expenses), or add a missing slip like an RRSP contribution receipt.

Two timing rules:

- **Wait for your notice of assessment** before asking for a change.
- **One request at a time.** If you've already asked for a change, wait for the CRA's answer before asking for another.

A change request can't be used to apply for benefits or credits, make or revise an election (pension splitting is an exception that Change my return accepts; see below), or move a refund to another CRA account. It also can't update your personal details, such as your address, direct deposit, marital status or name. Update those with the CRA separately.

## Three ways to ask

**Change my return, in your CRA account.** Sign in, go to Tax returns, choose Change my return, pick the year and follow the steps. Keep the confirmation number and summary of changes. It works for most situations, and it can also apply loss carry-backs, make an election to split pension income with your spouse or common-law partner (the CRA processes a change to the split only if both of you ask for it), or claim the disability tax credit once it's been approved.

**ReFILE, in certified tax software.** If you filed with certified software, look for the ReFILE option. It doesn't have to be the same software you filed with.

**Form T1-ADJ, by mail.** Fill in the form with the year and the changes, attach supporting documents for the whole amount (including amounts you claimed before without sending proof), and mail it to your tax centre. Send it separately from your current year's return.

The CRA says online requests are processed within two weeks and mailed ones within 19 weeks. Some take up to 35 weeks, including changes covering several returns, years past the normal three-year reassessment period, loss carry-backs, pension splitting, and requests where the CRA has to ask you for more information. Any refund is sent as soon as the request is processed.

## How far back you can go

- **Change my return** covers the 10 previous calendar years. A request made in 2026 can change returns for 2016 or later.
- **ReFILE** covers only recent years. The CRA's tax software pages list 2022 to 2025 for the season that runs until January 29, 2027. For an older year, use Change my return or mail.
- **Older years** can be changed by mail, but the CRA can't issue a refund for a change requested more than 10 calendar years after the end of the tax year.

Some returns can be changed only by mail, such as a bankruptcy return, an optional return for someone who died, or a return filed with the wrong province or territory.

## Mistakes to avoid

- Don't file a second return for the same year to fix one you've already sent. Wait for your notice of assessment, then ask for a change.
- Don't put a T1-ADJ in the same envelope as this year's return.
- Don't file an objection just to add something you forgot. A change request is the route for that, and the CRA notes it may be faster to let a pending change request finish than to object.

For common errors to avoid in the first place, see [common tax-return mistakes](https://taxnotes.ca/guides/common-filing-mistakes/).

## If you disagree: file an objection

An objection is for when you think the CRA misinterpreted the facts or applied the tax law incorrectly in a notice of assessment or reassessment, or in a notice about your benefits or credits.

**Deadline.** For individuals, it's whichever is later:

- one year after the filing deadline for that return, or
- 90 days after the date on the notice.

If the dispute is about TFSA or RRSP contributions, the deadline is 90 days from the notice. If you missed the deadline because you were trying to sort it out with the CRA, or because of circumstances beyond your control, you can ask for an extension up to one year after the deadline.

**How.** Online, choose "Register my formal dispute" in your CRA account; you'll get a case number to use when you send documents. Or mail Form T400A, or a signed letter, to the Chief of Appeals at the Appeals Intake Centre. Explain what you disagree with and why, and include the facts and supporting documents.

**Paying while you wait.** In most cases you don't have to pay disputed income tax until the CRA finishes reviewing your objection. But interest keeps adding up on any amount owing while it's in dispute, so paying some or all of it limits the interest.

If you disagree with the CRA's decision on your objection, you can appeal to the Tax Court of Canada.

## Quebec residents

Changes to your Quebec return go to Revenu Québec. Don't file a new return; instead use:

- **My Account for individuals,** for the current year and the three before it (the lines you can change vary by year),
- **the same authorized software** you filed with, for those years, sending the changed return online or by mail but not both, or
- **form TP-1.R-V,** Request for an Adjustment to an Income Tax Return, by mail with supporting documents. It's required for older years or a return still being processed, among other cases.

Requests for a refund or lower tax can generally go back 10 calendar years.

**Objecting.** If you think Revenu Québec misread the facts or misapplied the law, you typically have 90 days, counted from the day after the notice date. Individuals may instead have until one year after that year's filing deadline, if that's later and the assessment was under the Taxation Act. Object in My Account, or mail form MR-93.1.1-V or a letter, with a copy of the notice and your documents. Interest keeps running. Late? You can apply for an extension within one year after the objection deadline passes. If the notice was based on CRA information and you've already objected to the CRA, you needn't object to Revenu Québec too.

## In short

- Read your notice of assessment as soon as it arrives.
- Missed something? Wait for the notice, then use Change my return or ReFILE (or Form T1-ADJ by mail).
- Think the CRA got it wrong? Object by the deadline, and consider paying to limit interest.

## Sources

1. [Notices of assessment - NOA or NOR – Personal income tax](https://www.canada.ca/en/services/taxes/income-tax/personal-income-tax/after-you-file/noa-nor.html) (canada.ca)
2. [Changing a tax return](https://www.canada.ca/en/services/taxes/income-tax/personal-income-tax/after-you-file/change-return.html) (canada.ca)
3. [Help using the "Change my return" service in your CRA account](https://www.canada.ca/en/revenue-agency/services/e-services/digital-services-individuals/account-individuals/change-return.html) (canada.ca)
4. [T1-ADJ T1 Adjustment Request](https://www.canada.ca/en/revenue-agency/services/forms-publications/forms/t1-adj.html) (canada.ca)
5. [Federal income tax and benefit information for 2025](https://www.canada.ca/en/revenue-agency/services/forms-publications/tax-packages-years/general-income-tax-benefit-package/5000-g.html) (canada.ca)
6. [Tax software for filing personal taxes](https://www.canada.ca/en/services/taxes/income-tax/personal-income-tax/how-file/tax-software.html) (canada.ca)
7. [Check CRA processing times](https://www.canada.ca/en/revenue-agency/corporate/contact-information/check-cra-processing-times.html) (canada.ca)
8. [File an objection – Income tax](https://www.canada.ca/en/revenue-agency/services/about-canada-revenue-agency-cra/complaints-disputes/file-objection-cppei-appeal-minister/income-tax.html) (canada.ca)
9. [Income tax objections decision tree](https://www.canada.ca/en/revenue-agency/services/about-canada-revenue-agency-cra/complaints-disputes/file-objection-cppei-appeal-minister/income-tax-decision-tree.html) (canada.ca)
10. [NETFILE](https://www.canada.ca/en/services/taxes/income-tax/personal-income-tax/how-file/tax-software/send-return/netfile.html) (canada.ca)
11. [Correcting an Error or Omission – Revenu Québec](https://www.revenuquebec.ca/en/citizens/income-tax-return/correcting-an-error-or-omission/) (revenuquebec.ca)
12. [TP-1.R-V Request for an Adjustment to an Income Tax Return – Revenu Québec](https://www.revenuquebec.ca/en/online-services/forms-and-publications/current-details/tp-1-r-v/) (revenuquebec.ca)
13. [Objection – Revenu Québec](https://www.revenuquebec.ca/en/one-mission-concrete-actions/informing-you-of-your-rights/your-options-for-recourse/objection/) (revenuquebec.ca)
14. [Situations In Which You Can File an Objection – Revenu Québec](https://www.revenuquebec.ca/en/one-mission-concrete-actions/informing-you-of-your-rights/your-options-for-recourse/objection/situations-in-which-you-can-file-an-objection/) (revenuquebec.ca)
15. [Time Limit for Filing a Notice of Objection – Revenu Québec](https://www.revenuquebec.ca/en/one-mission-concrete-actions/informing-you-of-your-rights/your-options-for-recourse/objection/time-limit-for-filing-a-notice-of-objection/) (revenuquebec.ca)
16. [How to File a Notice of Objection – Revenu Québec](https://www.revenuquebec.ca/en/one-mission-concrete-actions/informing-you-of-your-rights/your-options-for-recourse/objection/how-to-file-a-notice-of-objection/) (revenuquebec.ca)
17. [Applying for an Extension of the Time Limit for Filing an Objection – Revenu Québec](https://www.revenuquebec.ca/en/one-mission-concrete-actions/informing-you-of-your-rights/your-options-for-recourse/objection/applying-for-an-extension-of-the-time-limit-for-filing-an-objection/) (revenuquebec.ca)

Tax figures in this guide come from the TaxNotes.ca rates tables (https://taxnotes.ca/rates/), which cite the Canada Revenue Agency and, for Quebec, Revenu Québec.

Last reviewed: October 11, 2026

How to cite: "Changing your return, and disputing an assessment", TaxNotes.ca, last reviewed 2026-10-11, https://taxnotes.ca/guides/changing-your-return/. For a figure or rule, also cite the official source listed above.

Licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to share and adapt with attribution: https://taxnotes.ca/reproducing-our-content/