26 U.S. Code § 2054 - Losses
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 losses incurred during the settlement of estates arising from fires, storms, shipwrecks, or other casualties, or from theft, when such losses are not compensated for by insurance or otherwise.
Source(Aug. 16, 1954, ch. 736, 68A Stat. 390.)