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Changing / Amending Your Tax Return
Income Tax Act S. 152(4.2)
Requesting a Tax Return Change Online
Requesting a Tax Return Change by Mail
Processing Time for Tax Return Amendments
Canada Revenue Agency (CRA) Resources
Tax Return Amendment Timing
If you've filed your return and then determine that you need to make a change, either because you have received another T-slip, or because you didn't claim an expense and later learned it was deductible, you can request an adjustment to your tax return. However, wait until you get your Notice of Assessment (NOA) from Canada Revenue Agency (CRA) before making any changes.
The time limit for filing most adjustments to your tax returns by mail is ten (10) years. For a late or amended pension splitting election the time limit is three (3) years - see our Pension Splitting article.
You can request the change for your most recent return, or your returns for the previous 9 tax years, either online or by mail. In 2025, you can request a change for the 2015 or later taxation years.
If you used a tax professional to file your tax return, they can also file an amendment for you.
Requesting a Tax Return Change Online
Requesting a change online is very simple, and is done by logging into your account at the CRA My Account page. You can request changes to more than one tax year in one session, but each tax year is done separately.
There are some changes you cannot make using My Account. See the link at bottom to the CRA Change my return information for exclusions.
When you log into My Account, if it shows a link to your most recent assessment on the Overview page, you can select the Change my return icon in order to make a change. For a prior year, click on
 | Go to Tax returns details, then |
| Click on the Status of return (Assessed or Reassessed) for the year you want to revise. |
| Once at the assessment page, go to the bottom of the page and click on the Change this return icon. |
| You will be prompted for the line number that you wish to change on your tax return. |
If you are trying to correct a prior return because you didn't enter all your RRSP contributions, see our article RRSP Contribution Not Recorded Last Year.
You can also use the online request if you forgot to apply for the GST/HST tax credit when you filed your tax return.
ReFILE Online Filing
If you filed your return using tax preparation software, you can use the same software to change your return, using CRA's ReFILE service (see link at bottom). CRA's Certified tax software for the NETFILE program indicates what level of ReFILE service each software product provides. ReFILE can be used to file amendments for the immediately past tax year and 3 previous tax years. The dates of availability for ReFILE are the same as for NetFILE.
Some things cannot be changed using ReFILE - see the CRA web page How to change your return, and scroll down to ReFILE.
To do this in your tax software, instead of Open an existing return, you probably have to choose Change a filed return.
Requesting a Tax Return Change by Mail
You can obtain a form T1-Adj, T1 Adjustment Request from the CRA web site, complete it and mail it in, along with documents supporting your change request.
Processing Time for Tax Return Amendments
CRA will either send you a reassessment notice indicating changes that were made to your return, or will explain in a letter why the requested changes were not made, hopefully by their service standard processing time.
The CRA service standard for processing time is 2 weeks for an electronic request, for straightforward taxpayer-requested adjustments only.
The CRA service standard for processing time is 8 weeks for a mailed request, for straightforward taxpayer-requested adjustments only.
As of March 16, 2025, their check CRA processing times indicates that for both electronic and mailed amendment requests, their goal is 20 weeks for a complex adjustment request. This excludes requests for international and non-resident individuals, and emigrants.
Canada Revenue Agency (CRA) Resources
ReFILE: Online adjustments for income tax and benefit returns
Check CRA Processing Times for Various Services
Revised: March 16, 2025