Fill Out CRA Form T1-ADJ Online
T1 Adjustment Request
Canada Revenue Agency
Requests a change to a personal income tax return that has already been filed and assessed.
Reviewed July 2026
How it works
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Form T1-ADJ, T1 Adjustment Request, is how you ask the Canada Revenue Agency to change a personal income tax return that has already been filed and assessed. Maybe a slip arrived after you filed, you missed a deduction, or you entered a number incorrectly. Rather than filing the return again, you identify the specific lines that should change and the CRA reassesses the return.
You can complete the T1-ADJ in the Universal PDF editor, enter the line numbers, previous amounts, and revised amounts on screen, and download the PDF to mail to the CRA with your supporting documents. One form covers one tax year, so use a separate T1-ADJ for each year you want changed.
What is Form T1-ADJ used for
The form requests changes to specific lines of an assessed T1 return: adding income from a late slip, claiming a missed deduction or credit, or correcting an error. After reviewing the request, the CRA issues a notice of reassessment showing the revised result, or a letter explaining why the change was not made.
Paper is not the only route. CRA My Account offers Change my return, and certified tax software offers ReFILE for returns filed electronically. The T1-ADJ is the standard option when you prefer paper or cannot use the online services.
Who files Form T1-ADJ
Any individual who has received a notice of assessment for the year in question can request an adjustment, or an authorized representative can do it for them. Wait until the original return is assessed; a change request sent before assessment cannot be processed against the return.
The CRA generally accepts adjustment requests going back a number of prior years, within the limits described in its published guidance, so older mistakes and missed credits are often still fixable.
How to fill out Form T1-ADJ
The form is organized around exact line changes:
- Identification: your name, address, social insurance number, and the tax year being adjusted.
- Line details: for each change, the line number from the return, the amount previously claimed, the revised amount, and the difference.
- Explanation: a short description of why each change is needed, such as a slip received after filing.
- Supporting documents: attach slips, receipts, or schedules that back up every change you request.
- Representative section: complete it if an accountant or other representative is submitting on your behalf.
- Signature: sign and date the request; unsigned requests are returned.
Where to send it
Mail the completed form and documents to the tax centre that serves your area; the current addresses are listed on the official CRA website. Processing times for paper adjustments are generally longer than for changes submitted through CRA My Account, and the CRA publishes its current service standards online.
Frequently asked questions
No. Never file a second return for the same year. Request changes to the assessed return through Change my return, ReFILE, or the T1-ADJ.
The CRA accepts requests for a limited number of prior years, described in its published guidance. If your change falls near the boundary, check the current rules or ask a tax professional.
Yes, but use a separate T1-ADJ for each tax year and include the supporting documents for each year's changes.
The CRA reviews the request and either issues a notice of reassessment with the revised amounts or sends a letter explaining why the adjustment was not made.
No. Send only the T1-ADJ and the documents that support the specific changes you are requesting.
Usually yes. Change my return in CRA My Account and ReFILE through certified software are generally processed faster than paper requests.
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