N.J. Stat. Ann. § 26:3-15

In a township having a population of not more than twenty thousand inhabitants, which is subject to the provisions of this subdivision of this article, in case of the death, removal, or resignation of an assessor before the time of electing his successor, the township clerk shall succeed the assessor as a member of the local board, and shall continue as a member until an assessor shall be elected or appointed.