If you're the executor of an estate, you must pay back income taxes owed by the decedant before you can disperse assets to beneficiaries.
This is the finding of United States v. McNicol, No. 15-2214 (1st Cir. 2016).
At the time decedant's death, the decedant owed over $340,000 in unpaid federal income tax liabilities. Since these liabilities exceeded the value of his estate, the estate was insolvent.
Nevertheless, the estate's executor distributed assets to herself. The IRS sued for payment of the back income taxes, and the executor lost on appeal.