Can I edit my file return and how do I get back to it without making a new refile, it seems I forgot to mention to split pension income

No. You can’t edit a return that has been filed via NETFILE, unless you are using REFILE. Also, none of the changes you make will be sent to the Canada Revenue Agency (CRA) unless you complete the REFILE process, or send the adjustment via another method, like My Account or mailing in Form T1-ADJ, T1 Adjustment Request.

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