If you have already started a ReFile and have made your changes, you can submit your return to the Canada Revenue Agency (CRA) in the same way you did when first filed your return. To get there in TurboTax Online, select File > Get Started from the bottom of the left side menu. 

For more information, check out: TurboTax - Amending My Tax Return

and, Canada Revenue Agency - ReFILE

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