N.C. Gen. Stat. § 163-226.1: Absentee voting in primary.

A qualified voter may vote by absentee ballot in a partisan primary provided the qualified voter is affiliated, at the time the qualified voter makes application for absentee ballots, with the political party in whose primary the qualified voter wishes to vote, except that an unaffiliated voter may vote in a party primary if permitted under G.S. 163-119. The official registration records of the county in which the voter is registered shall be proof of whether the qualified voter is affiliated with a political party and of the party, if any, with which the qualified voter is affiliated. (1977, c. 469, s. 1; 1999-455, s. 2; 2017-6, s. 3; 2018-146, s. 3.1(a), (b).)