Under what circumstances are property taxes and certain other expenses owed at death deductible on both form 706 and form 1041?

1) the decedent's will did not provided instructions.

2) the amounts owed were paid by the estate, but could have been deducted on the decedent's return if they had been paid prior to death.

3) the amounts owed were also simultaneously deducted on the decedent's final return.

4) the amounts due were paid by the decedent prior to death but the payments were not received until after the decedent had passed away.

* This question has been asked and answered three times, with three different expert answers. Please provide reference with answer. Thank you.