26 U.S.C. § 2058: State death taxes

For purposes of the tax imposed by section 2001, the value of the taxable estate shall be determined by deducting from the value of the gross estate the amount of any estate, inheritance, legacy, or succession taxes actually paid to any State or the District of Columbia, in respect of any property included in the gross estate (not including any such taxes paid with respect to the estate of a person other than the decedent). 4 years after the filing of the return required by section 6018, or a petition for redetermination of a deficiency has been filed with the Tax Court within the time prescribed in section 6213(a), the expiration of 60 days after the decision of the Tax Court becomes final, an extension of time has been granted under section 6161 or 6166 for payment of the tax shown on the return, or of a deficiency, the date of the expiration of the period of the extension, or 60 days from the date of mailing by certified mail or registered mail by the Secretary to the taxpayer of a notice of the disallowance of any part of such claim, 60 days after a decision by any court of competent jurisdiction becomes final with respect to a timely suit instituted upon such claim, or 2 years after a notice of the waiver of disallowance is filed under section 6532(a)(3).