South Carolina's tax calculation starts with Federal Taxable Income, so there is no option to itemize or take the standard deduction. Federal Taxable Income is calculated after taking federal exemptions (personal and dependency) and the standard or itemized deductions.
You can preview this calculation at the SC department of revenue HERE. Also, you can take a look at your SC return currently calculating in TurboTax, by following the instructions below to Preview my 1040. Once there, you'll see a tab to the top right for your SC state return. https://ttlc.intuit.com/replies/3302322
However, many states start with Federal Adjusted Gross Income (AGI- a subtotal before personal/dependency exemptions and standard/itemized deductions). These states often allow taxpayers to itemize, even while taking the standard deduction at the federal level. Often this is common because it's easier to qualify to itemize at the state level.
Maybe there's some confusion with another state? Let me know more details and I can assist you.
