South Carolina estimated tax due dates for 2026
South Carolina estimated income tax payments for tax year 2026 are due April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027. That matches the federal schedule. Below: who has to pay, how to avoid an underpayment penalty and where to pay, with the official source.
| 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.
