S.C. Code Ann. § 7-11-15
In order to qualify as a candidate to run in the general election, all candidates seeking nomination by political party primary or political party convention must file a statement of intention of candidacy between noon on March sixteenth and noon on March thirtieth as provided in this section.
(3) Candidates seeking nomination for a countywide or less than countywide office shall file their statements of intention of candidacy with the county executive committee of their respective party.
Except as provided herein, the county executive committee of any political party with whom statements of intention of candidacy are filed must file, in turn, all statements of intention of candidacy with the county election commission by noon on the tenth day following the deadline for filing statements by candidates. If the tenth day falls on Saturday, Sunday, or a legal holiday, the statements must be filed by noon the following day. The state executive committee of any political party with whom statements of intention of candidacy are filed must file, in turn, all the statements of intention of candidacy with the State Election Commission by noon on the tenth day following the deadline for filing statements by candidates. If the tenth day falls on Saturday, Sunday, or a legal holiday, the statements must be filed by noon the following day. No candidate's name may appear on a primary election ballot, convention slate of candidates, general election ballot, or special election ballot, except as otherwise provided by law, if (1) the candidate's statement of intention of candidacy has not been filed with the County Election Commission or State Election Commission, as the case may be, by the deadline and (2) the candidate has not been certified by the appropriate political party as required by Sections 7-13-40 and 7-13-350, as applicable. The candidate's name must appear if the candidate produces the signed and dated copy of his timely filed statement of intention of candidacy.
The statement of intention of candidacy required in this section and in Section 7-13-190(B) must be on a form designed and provided by the State Election Commission. This form, in addition to all other information, must contain an affirmation that the candidate meets, or will meet by the time of the general election, or as otherwise required by law, the qualifications for the office sought. It must be filed in triplicate by the candidate, and the political party committee with whom it is filed must stamp it with the date and time received, sign it, keep one copy, return one copy to the candidate, and send one copy to either the county election commission or the State Election Commission, as the case may be.
If, after the closing of the time for filing statements of intention of candidacy, there are not more than two candidates for any one office and one or more of the candidates dies, or withdraws, the state or county committee, as the case may be, if the nomination is by political party primary or political party convention only may, in its discretion, afford opportunity for the entry of other candidates for the office involved; however, for the office of State House of Representatives or State Senator, the discretion must be exercised by the state committee.
The provisions of this section do not apply to nonpartisan school trustee elections in any school district where local law provisions provide for other dates and procedures for filing statements of candidacy or petitions, and to the extent the provisions of this section and the local law provisions conflict, the local law provisions control.