I am trying to refile a 2023 return to add a missing T4A, when doing so it says refile not accepted by CRA. The NOA for the original return has been received. I tried using the new 8 digit code from the 2023 NOA, as well as the 8 digit code used to file the original return( which would be on the 2022 NOA), neither work. Any suggestions would be helpful.

I did notice on the refile page that the 2023 tax year is not listed as one of the years in which you can refile.