Enterprise
Individual & Small Business
| Payment | South Carolina due date |
|---|---|
| 1 | |
| 2 | |
| 3 | |
| 4 |
Federal 2026 estimated tax due dates, for comparison: April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027.
Who must pay South Carolina estimated tax?
You must file a Declaration of Estimated Tax if you expect to owe an Income Tax liability of $100 or more with the filing of your SC1040, Individual Income Tax Return. Exceptions: qualifying farmers/commercial fishermen, and individuals whose prior-year tax liability was $0 for a full 12 months.
How do you avoid a South Carolina underpayment penalty?
Penalty may apply if you do not pay at least 90% of the total tax due. Generally avoided by timely payments equal to 100% of the prior-year SC1040 tax (12-month year, return filed); 110% if prior-year AGI (federal guidelines with SC adjustments) was more than $150,000 (no separate MFS figure stated). The last payment can be skipped by filing the SC1040 by February 1 and paying the full balance.
How much should you pay?
Start with your federal estimate: the free Quarterly Estimated Tax Calculator works out your 2026 federal payments and safe harbor. South Carolina figures its own tax, so the state amount is separate.