South Carolina State Income Tax Return: SC1040, Deadlines, Refunds

To file a South Carolina state income tax return, complete Form SC1040 and submit it to the South Carolina Department of Revenue, either electronically through MyDORWAY or approved tax software, or on paper by mail. Your federal taxable income is the starting point, and you adjust it with South Carolina additions, subtractions, and credits to reach what you owe the state. For the 2025 tax year (returns normally due April 15, 2026), the SCDOR has automatically extended the deadline to October 15, 2026 to give filers time to adjust to tax law changes under H. 4216.¹

Who Has to File

A simple rule covers most people: if you filed a federal return, you almost certainly need to file a South Carolina return too. The statute (Section 12-6-4910) ties the filing threshold to the federal personal exemption plus the applicable standard deduction, which for most single filers means any meaningful amount of earned income triggers the obligation.²

Full-year residents report all income, no matter where it was earned. Nonresidents and part-year residents owe South Carolina tax only on income sourced in the state: wages for work physically performed here, rent from South Carolina property, profits from a business operating here. Part-year residents can pick their approach, filing as a full-year resident and claiming a credit for taxes paid to another state, or filing as a nonresident and reporting only South Carolina-source income. Nonresidents and part-year residents attach Schedule NR to the SC1040 to prorate income and deductions.³

What to Gather Before You Start

Pull together your completed federal Form 1040, every W-2 showing South Carolina withholding, any 1099s for investment or miscellaneous income, and Social Security numbers for yourself, your spouse, and any dependents. The SC1040 and its instructions are posted on the SCDOR website and are also built into major commercial tax software.⁴⁵

How the SC1040 Is Built

Your federal taxable income is the first number on the SC1040. That figure already reflects your federal standard or itemized deduction, so you are not rebuilding your deductions from scratch. From there, you apply South Carolina additions and subtractions to reach your state taxable income.⁵

Additions

Additions raise your South Carolina taxable income above the federal figure. The most common one is interest from bonds issued by other states. That interest is usually exempt from federal tax, but South Carolina taxes it, so you add it back on the state return.⁵

Subtractions

Subtractions reduce what you owe. South Carolina does not tax Social Security benefits or railroad retirement income that appeared on your federal return, so those come off. The state also offers a retirement income deduction for qualified retirement distributions: up to $3,000 if you are under 65, and up to $10,000 if you are 65 or older. Military retirement income has its own deduction line.⁵

Credits

Once your tax is calculated, credits reduce the amount owed dollar for dollar. Common ones include the two-wage earner credit for married couples filing jointly where both spouses have earned income, and the child and dependent care credit.⁶ Keep the paperwork that supports each credit, such as dependent care provider receipts, in case the SCDOR asks for verification.

Deadline and Extensions

The regular South Carolina deadline is April 15, matching the federal date. For 2025 returns, the SCDOR has automatically pushed the deadline to October 15, 2026, and you don’t need to request anything to get it.¹

In a typical year, a federal extension automatically covers your South Carolina return as long as you don’t owe state tax. If you do owe, request a state extension through MyDORWAY by making an estimated payment (the payment doubles as the extension request), or mail Form SC4868. An extension gives you more time to file but not more time to pay. To avoid the late-payment penalty, you need to have paid at least 90% of your tax by the original due date.⁷

How and Where to Submit

E-filing is the fastest and most reliable option. MyDORWAY is the SCDOR’s free online portal for filing returns, paying tax, and communicating with the department.⁸ Most commercial tax software supports South Carolina e-filing as well.

If you file on paper, the address depends on whether you owe:⁹

Refund or zero balance: SC1040 Processing Center, PO Box 101100, Columbia, SC 29211-0100
Balance due: Taxable Processing Center, PO Box 101105, Columbia, SC 29211-0105

Free Preparation Help

If you earn roughly $58,000 or less, have a disability, or are elderly, you may qualify for free tax preparation through the Volunteer Income Tax Assistance program. IRS-certified volunteers prepare and e-file both federal and state returns at no charge. To find a VITA site in South Carolina, call 2-1-1 or visit SC211.org.

If You Owe

MyDORWAY is the recommended way to pay. You can pay from a checking or savings account or by credit card (Visa, Mastercard, American Express, or Discover) with no additional fee on MyDORWAY.¹⁰ You can also mail a check or money order with your return.

If you cannot pay in full by the deadline, the SCDOR offers payment plan agreements lasting 12 to 48 months depending on how much you owe. To qualify, you need a bank account on your request form and must allow the SCDOR to draft the scheduled payments automatically. If you refuse automatic bank drafts, you must put 20% down upfront.¹¹

While the plan is active you must file every return on time and pay all new taxes in full, including estimated payments. If you fall out of compliance the agreement defaults and the SCDOR can take immediate collection action. Interest keeps accruing on the unpaid balance even while you are on a plan.¹¹

Tracking Your Refund

After filing, use the “Where’s My Refund?” tool on the SCDOR website to check your return’s status. It’s available around the clock.¹²

Expect up to eight weeks from the date you e-filed, or from February 2, whichever is later. Paper returns take longer. Refunds come by direct deposit or paper check; direct deposit is faster because paper checks require the State Treasurer’s Office to print and mail them. Once your return is filed, you cannot change the delivery method for that refund.¹²

Penalties and Interest for Missing the Deadline

Missing the filing deadline costs more than missing the payment deadline, which is why the SCDOR tells taxpayers to file on time even if they cannot pay in full. The late-filing penalty is 5% of the unpaid tax per month (or partial month) the return is late, capped at 25%. The late-payment penalty is 0.5% per month on the unpaid balance, also capped at 25%. The two can stack, so a taxpayer who neither files nor pays could face combined penalties approaching 50% of the original tax.¹³

Interest runs on top of penalties. The SCDOR sets the rate quarterly using the same methodology as the IRS, and it compounds daily on unpaid balances until the balance reaches zero.¹⁴ Filing on time and paying whatever you can is always the cheapest path.

Do You Also Owe Quarterly Estimated Tax?

If you expect to owe $100 or more when you file your SC1040, South Carolina wants quarterly estimated tax payments during the year. This mainly affects the self-employed, freelancers, landlords, and anyone whose income is not subject to withholding. For calendar-year filers, the due dates are April 15, June 15, September 15, and January 15 of the following year. Pay through MyDORWAY or mail vouchers with Form SC1040ES. Underpaying triggers an interest charge when you file the annual return.¹⁵

1
South Carolina Department of Revenue. South Carolina Department of Revenue
2
South Carolina Legislature. South Carolina Code 12-6-4910 – Persons, Corporations, and Other Entities Required to Make Tax Returns
3
South Carolina Department of Revenue. New to SC Filing?
4
South Carolina Department of Revenue. IIT Forms
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South Carolina Department of Revenue. SC1040 – 2025 Individual Income Tax Return
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South Carolina Legislature. South Carolina Code 12-6-3330 – Two Wage Earner Credit for Married Individuals Filing Joint Return
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South Carolina Department of Revenue. SC4868 – Request for Extension of Time to File
8
South Carolina Department of Revenue. MyDORWAY
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South Carolina Department of Revenue. 2025 SC1040 Individual Income Tax Form and Instructions
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South Carolina Department of Revenue. IIT File and Pay Options
11
South Carolina Department of Revenue. Payment Plan Agreements
12
South Carolina Department of Revenue. Refunds
13
South Carolina Legislature. South Carolina Code 12-54-43 – Penalties
14
South Carolina Legislature. South Carolina Code 12-54-25 – Interest Due on Late Payments
15
South Carolina Department of Revenue. Individual Declaration of Estimated Tax