Deadline for decedent's final return is 3 1/2 months after normal years close
Explanation
Test Your Knowledge – Questions for Review – Topic C. Refund Claims, Extensions, & Amended Returns
The interest clock keeps running with the extension
An amended return can be filed by the later of the two dates
Deadline is 3 years from due date of the return filed (later than 2 paid)
Extension is for filing return, and not for paying tax
Later deadline is 2 years from the date tax was paid