It will take longer for the CRA to process your request if you send a letter instead of Form T1-ADJ.
For more information, visit the CRA's Web site.
If you need to make a change to any return you have sent us, do not file another return for that year. You should wait until you receive your notice of assessment before requesting any change to a return that has not been processed.
You can make changes yourself to your return online. To access our electronic service, simply log on to My Account and select the Change my return option. You can then enter and submit any changes to your most recent Income Tax and Benefit Return, or to your returns of the previous two years, and they will be sent directly to our processing systems. For example, you may want to increase a deduction you claimed or add information from a slip you received after you sent us your income tax return.
Only requests relating to tax years ending in any of the 10 calendar years before the year you make the request will be considered. For example, a request made in 2011 must relate to the 2001 or a later tax year to be considered.
It usually takes eight weeks before we complete the adjustment and mail you a notice of reassessment.