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South Carolina Estimated Quarterly Tax

South Carolina requires estimated quarterly tax payments if you expect to owe more than $100 in state tax. The safe harbor is paying 90% of your current year tax liability or 100% of your prior year tax. Payments are due on the same dates as federal (April 15, June 15, September 15, January 15).

Why It Matters

Self-employed workers and freelancers in South Carolina must make estimated quarterly payments for both federal and state taxes. Missing payments or underpaying can result in penalties from both the IRS and South Carolina Department of Revenue. South Carolina charges a 7.0% penalty rate on underpayments. Planning ahead helps you avoid surprises at tax time and manage cash flow throughout the year.

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How It Works

South Carolina estimated tax is calculated on your expected state taxable income for the year. File using SC1040ES through South Carolina Department of Revenue. Payments are divided equally (25% each quarter). Due dates are 2026-04-15, 2026-06-15, 2026-09-15, and 2027-01-15. The annualized income installment method is available for taxpayers with uneven income throughout the year.

Example

Single filer • $100,000 net SE income • 2026

Quarterly

$7,196

per quarter

Federal

$25,745

25.75%

Total Annual

$28,783

28.78%

Resources

South Carolina Estimated Tax Payments - Official Portal

Official South Carolina estimated tax payment portal administered by South Carolina Department of Revenue.

Source: South Carolina Department of Revenue

Frequently Asked Questions

Can I use the annualized income method in South Carolina?

Yes. South Carolina allows the annualized income installment method for taxpayers with income that varies significantly throughout the year (e.g., seasonal businesses). This method bases each installment on your actual income through that quarter, which can reduce early-year payments if most income arrives later.

How do I pay estimated taxes in South Carolina?

You can make estimated tax payments in South Carolina online through South Carolina Department of Revenue's payment portal, by mailing SC1040ES with a check, or through electronic funds transfer. Online payment is the fastest and provides immediate confirmation.

What is the estimated tax threshold in South Carolina?

South Carolina requires estimated quarterly payments if you expect to owe more than $100 in state income tax after withholding and credits. This applies to self-employed individuals, freelancers, and anyone with significant non-wage income.

What is the penalty for underpaying estimated taxes in South Carolina?

South Carolina charges an underpayment penalty at a rate of 7.0% per year on the underpaid amount. To avoid penalties, pay at least 90% of your current year tax liability or 100% of your prior year tax (110% if AGI exceeds $150,000).

When are estimated tax payments due in South Carolina?

South Carolina follows the same due dates as federal estimated payments: April 15, June 15, September 15, and January 15. Payments are made using SC1040ES through South Carolina Department of Revenue.

Key Terms

Additional Medicare Tax
An extra 0.9% tax on earned income above $200,000 (single) or $250,000 (married filing jointly).
Annualized Income Method
A calculation method allowing unequal quarterly payments for those with seasonal or irregular income.
EFTPS
Electronic Federal Tax Payment System. A free IRS online system for making federal tax payments.
Estimated Tax
Quarterly payments of expected annual tax liability made by those without sufficient withholding.
Form 1040-ES
The IRS form used to calculate and submit federal estimated tax payments.
Net Self-Employment Income
Revenue minus deductible business expenses. The starting point for self-employment tax calculation.
Safe Harbor
A threshold of estimated tax payment that, if met, protects you from underpayment penalties regardless of your actual tax liability.
Self-Employment Tax
The self-employed person's equivalent of FICA, covering both Social Security and Medicare taxes.
Social Security Wage Base
The maximum amount of earnings subject to Social Security tax ($184,500 for 2026).
Underpayment Penalty
Interest charged by the IRS when estimated tax payments are insufficient relative to your actual liability.
Employer FICA Contribution
The 7.65% of your salary that your employer pays for Social Security and Medicare — a hidden benefit contractors don't receive.

Last reviewed: 2027-07-01 • Applies to tax year: 2026