How to Makes Changes to Your Canadian Income Tax Return

What to do if you have to amend or update a filed return

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Filing Canadian income tax returns is a relatively straightforward process that can be done online. But mistakes happen, and sometimes tax returns need to be changed after they've been filed. 

If you have corrections or changes to your income tax return, there's not much you can do until you receive your Notice of Assessment from the Canada Revenue Agency.

Once you've filed your Canadian income tax return, if you realize you've made a mistake, you'll need to wait until you receive your Notice of Assessment to file them. 

You can request changes to tax returns for the previous 10 years. Changes to recent income tax returns can be made online; others must be done by mail. It usually takes about two weeks for the Canada Revenue Agency (CRA) to process requests made online. It takes about eight weeks for the CRA to make an adjustment and mail you a Notice of Reassessment. Processing may take longer depending on the nature and timing of the request.

Making Changes to Your Income Tax Return Online

To make changes to your most recent Canadian income tax return, or to Canadian income tax returns for the previous two years, you can use the My Account tax service. Once you log in, select "Change my return."

You can also change your address using the My Account tax service.

Making Changes to Your Income Tax Return by Mail

To make changes to a Canadian income tax return by mail, either write a letter with details of your request or complete a T1-ADJ T1 Adjustment Request form (in PDF). You can request changes for tax years ending in any of the previous 10 calendar years.

You must include:

  • Your social insurance number
  • Your address
  • A telephone number where you can be reached during the day
  • Supporting documentation for the changes you are requesting
  • Supporting documentation for your original claim, if you haven't sent it before.

Mail the changes to your tax center.