26 U.S.C. § 2058 — State death taxes

(a) Allowance of deduction. For the tax imposed by section 2001, determine the taxable estate by subtracting from the gross estate the estate, inheritance, legacy, or succession taxes actually paid to a State or the District of Columbia on property included in the gross estate. Do not subtract taxes paid for the estate of someone other than the decedent.

(b) Period of limitations. The deduction includes only taxes actually paid and claimed before the later of (1) four years after filing the return required by section 6018, or (2) the applicable later deadline described below. If a Tax Court^* deficiency^* petition was timely filed, the deadline is 60 days after the decision becomes final. If an extension under section 6161 or 6166 was granted to pay the reported tax or a deficiency, it is the extension’s expiration date. If a timely refund or credit claim was filed, the deadline is the latest expiration of (i) 60 days after the Secretary^* mails a certified or registered notice disallowing part of the claim, (ii) 60 days after a court decision on a timely suit becomes final, or (iii) two years after notice waiving disallowance is filed under section 6532(a)(3). Despite sections 6511 and 6512, a refund based on this deduction may be made if claimed within that period. The refund does not include interest.