According to the South Carolina website:
A Resident is an individual that is domiciled in South Carolina or an individual who intends to maintain a home in South Carolina and South Carolina is the center of their financial, social and family life.
A Nonresident is an individual that has a permanent home outside of South Carolina and the definition of resident does not apply.
A Part-Year Resident is an individual that moved into or out of the state during the tax year. This individual qualifies as a resident for only a portion of the tax year. You may choose the residency status that is the most beneficial for you when filing your return. With in the program, you will select Nonresident, and then complete the residency information with in this state return.
What if I am a resident but my spouse is not?
If a joint federal return was filed and one spouse is a resident of South Carolina and the other is not, file a joint South Carolina nonresident return. The resident spouse must report all income while the nonresident spouse reports only the income earned in the state.
If you file separate federal returns (MFS), you & your spouse must file a separate South Carolina return if they have income taxable by South Carolina.
For more information: