i used Turbo Tax online to prepare and file my return. I have received my assessment and paid the amount due. How do I amend the return and resubmit.

After you file

This TurboTax Canada FAQ tells you how you can do that using ReFile: I've filed my tax return. Can I still make changes?

You can login to TurboTax Canada Online 2024 here: https://ww1.2024.ca.turbotaxonline.intuit.com/