The South Carolina ST-3 sales tax return is how businesses with a South Carolina retail license or use tax registration report taxable sales and pay the state’s 6 percent sales tax, along with any local taxes, to the South Carolina Department of Revenue (SCDOR). It’s due by the 20th of the month after each reporting period, and most filers submit it monthly through the free MyDORWAY portal. If you had no taxable sales, you still file a zero return.
Who Has to File
Any business holding a South Carolina retail license or a use tax registration files the ST-3. That includes brick-and-mortar stores, service providers who collect sales tax, and businesses that buy goods from out-of-state vendors without paying sales tax at purchase. You file every period you’re registered, even when the return shows zero due. Skipping a zero return can trigger penalties and eventually put your retail license at risk.
Remote sellers with no physical presence in the state also register and file once they meet South Carolina’s economic nexus standard. The SCDOR requires them to obtain a retail license and begin collecting sales tax on the first day of the second calendar month after the threshold is met.1South Carolina Department of Revenue. Remote Sellers Marketplace facilitators like Amazon or Etsy collect and remit for sales made through their platforms, but if you sell through your own website, that’s on you.
When the ST-3 Is Due
Most businesses file monthly. The return and payment are due on the 20th of the month after the reporting period, so January sales are reported and paid by February 20th. When the 20th lands on a weekend or legal holiday, the deadline shifts to the next business day.2South Carolina Legislature. South Carolina Code 12-36-2570 – Time When Tax Payment Due; Monthly Report
If your sales tax liability doesn’t exceed $100 in any given month, you may qualify to file quarterly instead. Quarterly returns are due by the 20th of the month following quarter-end. You need SCDOR authorization to switch to that schedule; you can’t move to quarterly on your own.3South Carolina Legislature. South Carolina Code Title 12 Chapter 36 – Section 12-36-2580
Filling In the Return
The ST-3 follows a straightforward path: total everything you took in, subtract what’s exempt, apply the state rate, then add local taxes. Have your records organized before you start.
Gross Proceeds, Deductions, and Use Tax
Line 1 is your total gross proceeds: all cash, credit, and property received from retail transactions during the period, including delivery charges, installation fees, and anything else bundled into the sale price. Subtract allowable deductions to reach your net taxable amount. Common ones include sales for resale backed by a valid resale certificate, sales to the federal government, and sales of exempt items such as unprepared groceries, prescription medicine, and manufacturing machinery.4South Carolina Department of Revenue. Chapter 9 – Exemptions
Use tax goes on the same return. If you bought goods from out-of-state vendors and didn’t pay sales tax at purchase, you owe South Carolina’s 6 percent use tax on those items.5South Carolina Department of Revenue. Sales and Use Tax Index Office supplies ordered from an out-of-state website are a typical example. Report the purchase price and calculate the tax the same way you would for a retail sale.
Round dollar amounts to the nearest whole dollar, and keep documentation for every deduction. The SCDOR will ask for resale and exemption certificates during an audit.
Local Taxes on the ST-389
South Carolina counties and municipalities can impose additional local sales taxes when voters approve them. These include capital project taxes, school district taxes, education capital improvement taxes, and transportation taxes, among others.6South Carolina Department of Revenue. SC ST-389 – Schedule for Local Taxes If you make sales in any county with one of these taxes, report them on the ST-389, which accompanies the ST-3.
The ST-389 breaks down your taxable sales by county. Most local taxes are 1 percent, though counties with multiple overlapping local taxes can push the combined rate higher. The Catawba Tribal Tax is a notable exception at 7 percent. Report sales based on the county where delivery occurs, which is usually where your business sits but can differ for shipped goods.6South Carolina Department of Revenue. SC ST-389 – Schedule for Local Taxes Getting county allocation wrong is one of the more common errors the SCDOR flags, so double-check delivery locations for cross-county sales.
Maximum Tax Items
Certain big-ticket items are subject to a maximum tax of $500 per item rather than the standard 6 percent. The cap applies to motor vehicles, boats, aircraft, motorcycles, recreational vehicles, and horse trailers, among others. If you sell any of these, report them separately on the return so the cap is applied correctly.
Exemptions and Resale Certificates
The exemptions you’ll see most often on South Carolina sales:
- Unprepared food eligible for purchase with USDA food stamps is exempt from the state 6 percent tax, though local taxes may still apply unless the local ordinance specifically exempts them.4South Carolina Department of Revenue. Chapter 9 – Exemptions
- Drugs sold by prescription, prosthetic devices, and diabetic supplies.
- Machines used in manufacturing, processing, recycling, mining, or quarrying tangible personal property for sale.
- Residential electricity and fuel.
- Sales to the federal government.
When a buyer claims resale, they hand you a completed ST-8A resale certificate. It must include the purchaser’s name, address, type of business, description of items sold, South Carolina retail license number, and signature of an owner, partner, or officer.7South Carolina Department of Revenue. Resale Certificate Keep every certificate on file. If the SCDOR audits you and you can’t produce one, you’re liable for the uncollected tax. Buyers who misuse resale certificates face a separate penalty of 5 percent per month on the unpaid tax, up to 50 percent.8South Carolina Legislature. South Carolina Code Title 12 Chapter 54 – Section 12-54-43
The Timely Filing Discount
South Carolina gives businesses that file and pay on time a discount on the tax due:
- Tax due under $100: 3 percent discount.
- Tax due of $100 or more: 2 percent discount.
The discount is capped at $3,000 per state fiscal year for paper filers and $3,100 for electronic filers. Voluntarily registered out-of-state sellers who aren’t legally required to collect South Carolina tax get a higher cap of $10,000 per fiscal year.9South Carolina Legislature. South Carolina Code Title 12 Chapter 36 – Section 12-36-2610 The discount disappears entirely if your return or payment arrives even one day late. No partial credit for coming close.
How to Submit the Return
Filing Through MyDORWAY
The SCDOR recommends filing through MyDORWAY, its free online portal at MyDORWAY.dor.sc.gov. Log in, open the Accounts tab, scroll to your Sales & Use Tax account, and click “File a Return.”10South Carolina Department of Revenue. ST-3 Instructions The portal handles the math and rolls the ST-389 local tax schedule into the same workflow. You can pay by ACH debit or credit card with no convenience fees and schedule payments in advance.11South Carolina Department of Revenue. State Sales and Use Tax Return
MyDORWAY also adds $100 per year to your timely filing discount cap and confirms each transaction immediately. Electronic filing isn’t optional if your South Carolina tax liability reaches $15,000 or more per filing period.10South Carolina Department of Revenue. ST-3 Instructions
Mailing a Paper Return
If you file on paper, the mailing address depends on whether you owe tax:
- Balance due: SCDOR, PO Box 100193, Columbia, SC 29202
- Zero due: SCDOR, PO Box 125, Columbia, SC 29214-0101
Paper returns must be postmarked by the due date. If the postmark falls after the 20th, the SCDOR treats the return as delinquent no matter when you dropped it in the mail.11South Carolina Department of Revenue. State Sales and Use Tax Return Paper processing is slower and doesn’t earn you the extra $100 discount bump.
Penalties for Late Filing or Late Payment
Missing the deadline triggers two penalties that run at the same time:
- Late filing penalty: 5 percent of the tax due for the first month (or fraction of a month), plus another 5 percent for each additional month the return remains unfiled, up to 25 percent.8South Carolina Legislature. South Carolina Code Title 12 Chapter 54 – Section 12-54-43
- Late payment penalty: 0.5 percent of the unpaid tax per month, up to the same 25 percent ceiling.8South Carolina Legislature. South Carolina Code Title 12 Chapter 54 – Section 12-54-43
Interest accrues on top of both, tied to the IRS underpayment rate. Because the late-filing penalty is ten times steeper than the late-payment penalty, filing on time with a partial payment is always better than not filing at all.
Keeping Your Records
South Carolina law requires you to keep records as long as their contents may become material to any tax administered by the SCDOR.12South Carolina Legislature. South Carolina Code Section 12-54-210 – Requirements as to Records In practice, hold onto sales records, purchase invoices, resale and exemption certificates, and filed returns for at least three years from the filing date, which is the standard audit window. If the SCDOR suspects you underreported by 25 percent or more, the review period extends to six years, and there’s no time limit when fraud is involved or no return was filed. Organizing records by filing period rather than by document type makes it far easier to respond if the SCDOR asks for documentation on a specific return.