46 U.S.C. § 53307

Under the income or excess profits tax laws of the United States, the basis for determining a gain or loss and for depreciation of a new vessel constructed, reconstructed, reconditioned, or acquired by the taxpayer, or for which purchase-money indebtedness is liquidated as provided in section 53310 of this title, with amounts from a construction reserve fund, shall be reduced by that part of the deposits in the fund expended in the construction, reconstruction, reconditioning, acquisition, or liquidation of purchase-money indebtedness of the new vessel that represents a gain not recognized for tax purposes under section 53306 of this title.