Since the South Carolina
Form 1099-G/INT you receive indicated an overpayment for 2015, reporting a prior-year South Carolina
tax refund or credit, you would enter
it just as you would a Form 1099-G.
Please see
the following TurboTax FAQ, "Where do I enter a South Carolina Department
of Revenue 1099-G/INT?":
https://ttlc.intuit.com/replies/4774036