Turbo Tax will not let me enter a T4A(OAS) for the 2020 tax year for someone that passed away in 2019. Just need to enter the supplement paid - box 21.

We are sorry for your loss. Please find included our TurboTax Article Deceased Returns: The Final Return

On this previous page, you will find Income reported on the final return includes: which will give you guidance about what to claim on the return.

Thank you for using TurboTax.