How to amend a T2 or CO-17 corporate return
What to do when a T2 or CO-17 already filed needs a correction: transmit an amended return from the same file, for the same business number and tax year end, instead of starting over.
Last checked October 27, 2026
When a return needs amending
A return that was transmitted and accepted is on file with the CRA or Revenu Québec. If an amount was wrong, a schedule was missing or a deduction was not claimed, the correction is an amended return for that same tax year, not a second original return.
Amending a T2
Corporations that must file the T2 electronically can transmit an amended T2 through Corporation Internet Filing with certified software. The amended return carries the same business number and tax year end as the original, and contains the complete return with the corrections, not only the changed lines.
Amending a CO-17
A CO-17 can be amended online with software authorized by Revenu Québec, or on paper with form CO-17.R, Request for an Adjustment of the Corporation Income Tax Return.
Source: Revenu Québec, CO-17.R.
In AuraTax: reopen the return, don't delete it
- Open the return that was transmitted: the same corporation, business number and tax year end.
- Make the changes. AuraTax keeps what was sent before, so you can see what you changed.
- Transmit it again; AuraTax sends it as an amended return.
Do not delete a transmitted return and start a new one. A new return for the same year would be sent as an original, and the history of what was filed would be lost.