Amend a T1 with the CRA: ReFILE, Change my return or T1-ADJ

Which method should you use to amend a T1?

There are three ways to change a filed T1, and all three need the notice of assessment first. If a change request is already in, you wait for the CRA's answer before sending another one canada.ca.

For preparers, the CRA's EFILE news page says you can file clients' amended T1 returns for 2022 to 2025 through ReFILE, and that EFILE and ReFILE are open from February 23, 2026 until January 29, 2027 canada.ca. The original return has to have been sent with certified software, but you don't need to use the same software to ReFILE it canada.ca.

Change my return reaches further back: a request made in 2026 can cover the 2016 return or any later year canada.ca. You need at least level 2 authorization on the client's account to use it as a representative (see how to get authorized).

What the CRA will not change through an adjustment request

An adjustment request is for reporting income (a missed T4 or tips), claiming deductions, credits or expenses, and adding a missing slip such as an RRSP receipt. The CRA's page lists what you can't do this way: apply for benefits or credits, make or revise an election, allocate a refund to another CRA account, or update personal details like address, direct deposit, marital status or name canada.ca.

Some returns can't go online at all and must be changed by mail with Form T1-ADJ canada.ca:

For a deceased client, only the final return can be adjusted online canada.ca. See the final return and rights or things return pages for those filings.

How far back can you amend, and what does the 10 year limit mean?

The CRA can't issue a refund for an adjustment request made more than 10 calendar years after the end of the tax year canada.ca. The rule comes from ITA subsection 152(4.2), which lets the CRA reassess an individual (other than a trust) or a graduated rate estate after the normal reassessment period, on an application made within 10 calendar years after the end of the year, to determine a refund or reduce an amount payable laws-lois.justice.gc.ca. Subsection 164(1.5) gives the matching power to refund the overpayment laws-lois.justice.gc.ca.

The window counts from the end of the tax year, not from the filing date or the assessment date. A client who finds an unclaimed 2016 medical receipt in November 2026 still has until December 31, 2026 to get the money back. On January 1, 2027, that year is closed for refunds.

Both subsections are limited to individuals (other than trusts) and graduated rate estates, which is why this window belongs to the T1 and not to the T2 or T3 laws-lois.justice.gc.ca.

Worked example: a 2022 change requested in October 2026

Your client's 2022 T1 was assessed on May 1, 2023. In October 2026 you find a missed $4,000 RRSP receipt for that year.

• The normal reassessment period for an individual is three years from the day the original notice of assessment was sent, under ITA subsection 152(3.1) laws-lois.justice.gc.ca. Here it ended May 1, 2026.
• The request is still well inside the 10 year refund window, which runs to December 31, 2032 (2022 plus 10 calendar years).
• ReFILE still accepts 2022 this season, so you can send it electronically until January 29, 2027 canada.ca.
• Because the year is past the normal 3 year period, the CRA flags it for longer handling: up to 35 weeks instead of about 2 canada.ca.

The result is a notice of reassessment for 2022 showing the $4,000 deduction. Had the same receipt been for 2021, ReFILE would no longer take it this season, and you would use Change my return or Form T1-ADJ instead.

For the full reassessment rules, including the extra three years for certain items, see the CRA reassessment period.

How to fill out and send Form T1-ADJ

Form T1-ADJ, T1 Adjustment Request, comes as a webform, a fillable PDF and a print PDF canada.ca. The fillable PDF must be downloaded and opened in Acrobat Reader version 10 or later, not in a browser.

On the form, give the tax year, each line you're changing and the revised amount. Attach supporting documents for the full amount claimed, including amounts claimed earlier without documents, and send the form separately from your client's current year return canada.ca.

The CRA's processing times page, last updated October 8, 2026, says complex adjustment requests run on a 35 week timeline from receipt to a notice of reassessment or a letter of explanation, and that intake is higher than normal canada.ca. When the CRA makes all or part of the change, it sends a notice of reassessment explaining anything it didn't change. When it makes no change, it sends a letter instead canada.ca.

Adjustment, objection or voluntary disclosure?

An adjustment request is for changes your client initiates. If you disagree with how the CRA assessed or reassessed the return, file a notice of objection instead, within its own deadline (see the notice of objection deadline).

If the correction adds unreported income for a year at least one year past its filing due date, the CRA points to the Voluntary Disclosures Program as an alternative canada.ca. The program grants relief case by case to taxpayers who correct errors or omissions, under rules that changed on October 1, 2025 canada.ca. The VDP page covers the relief levels and how to apply.