Here's some additional information on making an amendment to your return:
You already filed your tax return, it was accepted by the CRA, and
now you received additional forms or tax information or you need to
If so, you need to amend the tax return
you already filed. First, be sure the return was accepted by the CRA,
and do not change the return you already filed. Amended returns must be
filed on a new form called T1-ADJ, T1 Adjustment Request.
Follow these steps: