Hope this help here is the link to CRA
http://www.cra-arc.gc.ca/tax/individuals/topics/income-tax/changereturn-e.html
How to change your tax and benefit return
If, after receiving your Notice of Assessment, you want to make a change to your personal Income Tax and Benefit return, you can do so in one of the following ways.
By Internet
You can now make changes yourself to your Income Tax and Benefit Return online. To access our new, 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.
You cannot use this service to get general information or information about tax or matters related to investigations. To change your address, see How to change your address.
By mail
Send both of the following to your tax centre:
a completed form T1-ADJ T1 Adjustment Request, or a signed letter providing the details of your request (including the years of the returns you want us to change), your social insurance number, an address, and a telephone number where we can reach you during the day; and supporting documents for the changes you want to make and, if you have not sent them to us before, supporting documents for your original claim.
I have done my adjustment online for years. But the T1-adj form is very confusing to fill.
