Income taxes unpaid but attributable to income earned while the decedent was still living can be deducted on Form 706?

Yes, income taxes that remain unpaid but are attributable to income earned by the decedent while they were alive can be deducted on Form 706, the United States Estate (and Generation-Skipping Transfer) Tax Return. This deduction is allowed because it reflects the decedent's liabilities that were incurred during their lifetime. It is important for executors to accurately report these liabilities to ensure proper estate tax calculations.