S.C. Code Ann. § 12-6-3400 — Credit for income tax paid by South Carolina resident to another state

(A)(1) Resident individuals are allowed a credit against the taxes imposed by this chapter for income taxes paid to another state on income from sources within that state which is taxed under both this chapter and the laws of that state regardless of the taxpayer's residence.
(2) The credit allowed is the lesser of:
(a) the product of the fraction in which the numerator is total South Carolina income which is subject to income tax in another state and the denominator is total federal income adjusted by the modifications provided in Article 9 of this chapter and subject to allocation and apportionment as provided in Article 17 of this chapter, multiplied by South Carolina income tax before the credit allowed by this section; or
(b) the income tax actually paid to the other state on income taxed under this chapter.
(3) A copy of the income tax return filed with the other state must be filed with the South Carolina tax return at the time credit is claimed. If the credit is claimed because of a deficiency assessment notice, a copy of the notice and a receipt showing the payment must be filed.
(B) If a taxpayer is refunded or credited taxes paid to another state for which a credit has been allowed under this section, then a tax equal to that portion of the credit allowed is due and payable from the taxpayer within sixty days from the date the refund or the notice of the credit is received. If the amount of the tax is not paid within sixty days of receipt or notice, the taxpayer is subject to penalties and interest for failure to pay provided in Chapter 54 of this title.
(C) When a taxpayer is considered a resident of this State and is also considered a resident of another state under the laws of the other state, the department may, at its discretion, allow a credit against South Carolina income taxes for those taxes paid to the other state on income taxed under this chapter.