N.J. Stat. § 54:38-4
If after the payment of the tax hereby imposed there shall become due and payable a tax upon any future interest in any property under an instrument creating an executory devise or an estate in expectancy of any kind or character which is contingent or defeasible, under sections 54:36-3 to 54:36-7 of this title, or if by reason of any additional or corrected assessment by the state tax commissioner an additional inheritance, succession or legacy tax shall become due and payable under chapters 33 to 36 of this title (s. 54:33-1 et seq.), or under any subsequent enactment imposing taxes of a similar nature, the tax paid under this chapter shall be credited against the tax arising under said sections 54:36-3 to 54:36-7 or any additional tax as aforesaid, but the amount so credited shall not in any event exceed the amount of the tax so accruing. Nothing contained in this chapter shall reduce the amount of inheritance, succession or legacy taxes due and payable to the state under the provisions of said chapters 33 to 36 of this title, or under any subsequent enactment or entitle the estate of any resident decedent to a refund because the taxes paid thereunder shall exceed the amount of the credit under any federal revenue act in effect as of the date of death of the decedent.
N.J.S. § 54:38-4