Guide
Key South Carolina Tax Deadlines
The SCDOR automatically extended every 2025 South Carolina individual income tax return to October 15, 2026, but payment was still due April 15, 2026. The 2026 SC1040, the first under H.4216's new rates, is due April 15, 2027. SC S corporation and partnership returns are due the 15th day of the third month after year end (March 15, 2027 for calendar-year filers), and C corporation returns the 15th day of the fourth month (April 15, 2027).
South Carolina's calendar mostly tracks the federal one, with a few exceptions that catch businesses out: the 20th-of-the-month sales tax cycle, quarterly withholding returns due at the end of the following month, and local Charleston deadlines for property tax and business licenses. Under S.C. Code Section 12-60-50, a state tax deadline that falls on a Saturday, Sunday or legal holiday moves to the next business day, and we have applied that rule to the dates below. Federal dates are on our tax deadline calendar.
2025 SC1040: October 15, 2026 (automatic extension)
Best for: Individuals who have not yet filed their 2025 South Carolina return
On March 26, 2026, the SCDOR automatically extended the filing due date for all 2025 South Carolina individual income tax returns to October 15, 2026, with no action required. The extension covered filing, not payment: the SCDOR said penalties apply if at least 90% of the 2025 liability was not paid by April 15, 2026. H.4216 does not change 2025 returns.
- Due Thursday, October 15, 2026
- No extension form was needed
- Payment was due April 15, 2026
SC estimated tax: January 15, 2027
Best for: Individuals who expect to owe $100 or more when they file
The 2026 SC1040ES lists calendar-year installments on April 15, June 15 and September 15, 2026, and January 15, 2027. Instead of the January payment, you can file your 2026 SC1040 by February 1, 2027 and pay the full balance. The SCDOR's Information Letter 26-20 explains how H.4216 (Act 110) affects 2026 estimates, since the new two-bracket rates and the SC Income Adjusted Deduction apply to tax year 2026.
- Fourth 2026 installment: Friday, January 15, 2027
- Alternative: file and pay in full by Monday, February 1, 2027
- Recheck estimates against the new 2026 rates
Withholding returns: end of the month after each quarter
Best for: Employers with South Carolina withholding accounts
WH-1605 is filed for the first three quarters and WH-1606 for the fourth quarter and annual reconciliation. The SCDOR schedule is April 30, July 31, October 31 and January 31. Resident withholding payments follow the same frequency as your federal deposits. Weekend dates roll forward: the third-quarter 2026 return is due Monday, November 2, 2026 because October 31 is a Saturday.
- Q3 2026 WH-1605: Monday, November 2, 2026
- Q4 2026 WH-1606: Monday, February 1, 2027
- Q2 2027 WH-1605: Monday, August 2, 2027
W-2s to the SCDOR: January 31
Best for: Every South Carolina employer
The SCDOR says W-2 forms are due to employees, the IRS/SSA and the SCDOR by January 31. MyDORWAY is its preferred upload method, and it also accepts 1099-NEC and 1099-MISC. January 31, 2027 is a Sunday, so the deadline is Monday, February 1, 2027. For federal purposes, the 1099-NEC and 1099-MISC reporting threshold is $2,000 for payments made after December 31, 2025.
- 2026 W-2s: Monday, February 1, 2027
- No WH-1612 transmittal needed when uploading on MyDORWAY
- Federal 1099 threshold now $2,000
Sales and use tax: the 20th
Best for: Retailers and anyone holding an SC retail license
Monthly returns are due the 20th of the month after the period ends; quarterly returns are due April 20, July 20, October 20 and January 20; annual returns are due January 20. Several 20ths in the coming months land on weekends and roll forward to Monday.
- November 2026 period: Monday, December 21, 2026
- January 2027 period: Monday, February 22, 2027
- February 2027 period: Monday, March 22, 2027
S corporations (SC1120S): March 15
Best for: S corporations and LLCs taxed as S corporations
The SC1120S, including the annual report (Schedule D) and the license fee, is due the 15th day of the third month after year end: Monday, March 15, 2027 for calendar-year 2026. Paying on MyDORWAY submits an extension request, but there is no extension of time to pay. Nonresident shareholder withholding on the SC1120S-WH is due the same day and cannot be extended.
- 2026 SC1120S: Monday, March 15, 2027
- Extension to file up to six months (September 15, 2027)
- SC1120S-WH has no extension
Partnerships (SC1065): March 15
Best for: Partnerships and multi-member LLCs
Partnership returns and any partnership-level tax are due by the 15th day of the third month after the end of the business year, along with nonresident partner withholding. An extension of up to six months is available by paying on MyDORWAY or filing the SC8736, but there is no extension of time to pay.
- 2026 SC1065: Monday, March 15, 2027
- Extended due date: Wednesday, September 15, 2027
- Active trade or business election made on the return
C corporations (SC1120): April 15
Best for: C corporations and LLCs taxed as corporations
Corporations other than S corporations file on or before the 15th day of the fourth month after year end; the SC1120-T extension request is due the same day. The corporate rate is 5%, and the annual license fee is due with the return or extension request. For calendar-year 2026 that is Thursday, April 15, 2027.
- 2026 SC1120: Thursday, April 15, 2027
- Six-month extension to Friday, October 15, 2027
- License fee due with the return or extension
2026 SC1040: April 15, 2027
Best for: Individual filers
The SCDOR states that H.4216 applies from the 2026 tax year, with returns due April 15, 2027. The 2026 return starts from federal adjusted gross income, uses the new SC Income Adjusted Deduction and the 1.99% and 5.21% rate structure. If you file a federal extension, SC Revenue Procedure 17-1 says the SCDOR accepts it as a six-month SC extension; a separate SC4868 is needed only if you are making a payment.
- Due Thursday, April 15, 2027
- Federal extension carries over to SC
- Tax is still due April 15
Charleston County property tax: January 15
Best for: Owners of real and business personal property in Charleston County
Charleston County says taxes on real and other personal property (not motor vehicles) are due by January 15 of the following year without penalty. Penalties then step up: 3% after January 15, 10% in total after February 1, and 15% in total after mid-March, when the bill goes to the Delinquent Tax Department.
- 2026 bills: Friday, January 15, 2027
- Penalties cannot be waived
- Treasurer: (843) 958-4360
City of Charleston business license: April 30 and May 31
Best for: Businesses operating or earning income inside Charleston city limits
All City of Charleston business licenses expire on April 30. The City says the renewal fee is due May 1 and payable by May 31, and that a payment due on a weekend or observed holiday is timely on the next business day. May 31, 2027 is Memorial Day, so a payment on Tuesday, June 1, 2027 is timely. Penalties start at 5% of the unpaid fee for the first month.
- Licenses expire April 30, 2027
- Payment timely through Tuesday, June 1, 2027
- Unincorporated county and several towns license through Charleston County
South Carolina dates, late 2026 through 2027
| Date | Deadline |
|---|---|
| Thursday, October 15, 2026 | 2025 SC1040 (automatic extension); extended 2025 SC1120 |
| Monday, November 2, 2026 | Q3 2026 WH-1605 withholding return |
| Monday, December 21, 2026 | November 2026 monthly sales tax |
| Friday, January 15, 2027 | Fourth 2026 SC estimated payment; Charleston County property tax |
| Wednesday, January 20, 2027 | December monthly, Q4 quarterly and annual sales tax |
| Monday, February 1, 2027 | WH-1606 annual withholding; W-2s to the SCDOR; SC1040 filed and paid in full in place of the January estimate |
| Monday, March 15, 2027 | 2026 SC1120S and SC1065 |
| Thursday, April 15, 2027 | 2026 SC1040 and SC1120; first 2027 SC estimated payment |
| Friday, April 30, 2027 | Q1 2027 WH-1605; City of Charleston business licenses expire |
| Tuesday, June 1, 2027 | City of Charleston business license payment (May 31 is Memorial Day) |
| Wednesday, September 15, 2027 | Extended 2026 SC1120S and SC1065 |
| Friday, October 15, 2027 | Extended 2026 SC1040 and SC1120 |
A deadline most businesses do not know about
If the IRS changes the taxable income of a business, including a pass-through entity, S.C. Code Section 12-54-85 requires the business to notify the SCDOR in writing within 180 days of the final federal determination. The SCDOR can then assess the related state tax even after its normal 36-month window. If you are dealing with an IRS exam, put the state notice on the list from the start.
Keeping it manageable
Most missed South Carolina deadlines come from sales tax and withholding rather than income tax, because they recur and fall on odd days. Haigler CPA Group handles SC business returns and can keep the recurring filings on a monthly bookkeeping schedule. For the federal dates, see our tax deadline calendar.
Sources
- SCDOR: April 15 filing deadline extended for SC returns (March 26, 2026)
- SCDOR: Information about H. 4216
- SCDOR: 2026 SC1040ES Individual Declaration of Estimated Tax
- SCDOR: Withholding tax
- SCDOR: Sales tax due dates
- SCDOR: SC Revenue Procedure 17-1, return due dates and extensions
- S.C. Code Title 12, Chapter 60 (Section 12-60-50)
- City of Charleston: Business License Renewals
The information on this site is general in nature and is not tax, legal, or accounting advice for your situation. Tax law changes and the right answer depends on facts we would need to review with you. Please speak with a qualified professional before acting on anything you read here.
Questions people ask about this
When is my 2025 South Carolina income tax return due?
October 15, 2026. The SCDOR automatically extended all 2025 SC individual income tax returns to that date with no action required, but payment was due April 15, 2026.
Does South Carolina accept my federal extension?
Yes. Under SC Revenue Procedure 17-1, a federal extension gives an automatic six-month SC extension. You only need to file a separate SC extension if you are making a payment with it. An extension never extends the time to pay.
When are South Carolina sales tax returns due?
By the 20th of the month after the reporting period for monthly filers. Quarterly returns are due April 20, July 20, October 20 and January 20. If the 20th falls on a weekend or holiday, the deadline moves to the next business day.
When are SC S corporation and partnership returns due?
The 15th day of the third month after the tax year ends, which is March 15, 2027 for calendar-year 2026. Both can extend filing by up to six months, but not payment.
Does H.4216 change my 2025 return?
No. The SCDOR says H.4216 applies beginning with the 2026 tax year, with returns due April 15, 2027.
Keep reading
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- South Carolina Sales Tax for Small BusinessSales tax is the obligation small businesses most often discover late, because nothing about it is triggered by profit. It is triggered by making a sale, and it starts on the first one.
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- All Charleston tax & accounting guidesEvery list, choosing a CPA and the tax reference lists.
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