Short tax year? Or full year? (Deceased)

[NaySao]

I'm filing an extension for my father in law so we can have more time to get organized. But the extension asks if it's for the full year or partial year. He died in October but received interest on his investments through November. Do I just mark the form for the full year? Or am I supposed to mark it from 1/1 until 10/20? The 1099-INTs he received don't list months, only 2023.

Thank you.

[MinhT1]

Mark the tax return as being for the full year.

See this IRS document.

I'm sorry for your loss.