Louisiana Revised Statutes Tit. 47, § 2451. Claims and suits for refund

(1) Within fifteen months from the time the erroneous payment or overpayment was made by the taxpayer.

(2) Within six months after the judgment of the highest court in which any succession contest between the heirs and legatees becomes final.

(3) Within six months after a payment of federal estate tax, as to which tax a credit was allowed under the United States Internal Revenue Code for death taxes paid to the state of Louisiana, is refunded, in whole or in part, or a judgment of court for such refund becomes final, whichever is later.

(4) Within ninety days after filing an amended federal estate tax return if the credit allowed for death taxes paid to the state of Louisiana was reduced from the federal estate tax return filed immediately prior to the amended return.