If no candidate receives at least 50% of the vote in the primary, a runoff will be held between the top two vote-getters.

Voters who voted in a party's primary, can vote only in the runoff of the same party. Voters who did not vote in the primary, may vote in either party's runoff.

The primary is for Democratic and Republican candidates only. Candidates running unopposed for their Party's nomination will not appear on primary ballots.

A defeated primary candidate may not actively offer or campaign as a write-in candidate for the ensuing election. The use of posters or stickers on the ballot is not permitted. The voting machine provides for a voter to write-in a candidate. Write-in votes are not allowed in primary elections or the election of President or Vice-president.

While the state permits fusion (a candidate may be nominated by multiple parties), if a candidate runs for and looses a primary (of any party), the candidate cannot appear on the November ballot. [Section 7-11-10]

13 May 2022: Governor Henry D. McMaster (Republican) signed S 0108 {Rat #165} that bans fusion voting (candidates can run under the banner of mulitiple parties) effective in 2023.

The Alliance, Constitution, Green, Independence, Labor, Libertarian, United Citizens, and Working Families Parties may nominate by convention.

6 January 2023: The U.S. District Court strikes down the South Carolina U.S. House CD 1 boundaries as a violation of the Voting Rights Act. The court ordered the South Carolina General Assembly to present the Court with a remedial map no later than 31 March 2023. South Carolina Conference of the NAACP v Alexander, 3:21cv-3302.