I am sorry to hear of your loss.
Attempting to file a tax return for a deceased individual using their old account may result in the system assuming that the person is still filing for themselves. In such a case, it is advisable to create a new account and proceed from there.
When you start the return, TurboTax will ask who you’re preparing the return for. Select Someone else. Then it will ask if you are preparing a married or common law return. Once you’ve answered that question, you’ll then be asked if the person has passed away, and if you answer Yes, you’ll be prompted to enter the deceased’s date of death.
This FAQ has more information regarding preparing a return for a deceased person: https://turbotax.community.intuit.ca/community/product-information/help/can-i-prepare-a-return-with-...
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