2026 South Carolina Small Business Tax Deadline Calendar

For the 2026 tax year, South Carolina small business owners should watch four estimated-tax dates—April 15, June 15, September 15, and January 15, 2027—along with the March 15, 2027, deadline for calendar-year S corporations and partnerships and the April 15, 2027, individual filing deadline. Sales and use tax is generally due on the 20th of the following month, while local hospitality tax returns in places such as Summerville, SC and across the Lowcountry and Bluffton area are generally due by the 20th of each month. Moore Accounting Group helps business owners turn this calendar into a simple, proactive filing routine.

Tax deadlines are easier to manage when they are visible before they become urgent. This 2026 calendar is designed for calendar-year small businesses, including sole proprietors, single-member LLCs, partnerships, and S corporations. It focuses on the deadlines that most often affect businesses in Summerville, SC, the Lowcountry, and the Bluffton area. Your exact obligations can vary based on your entity type, payroll, industry, filing frequency, and local jurisdiction, so use this as a planning guide and confirm the details that apply to your business with Moore Accounting Group.

January 2026: Finish Last Year Strong

January 15, 2026: The fourth estimated federal and South Carolina income tax payment for the 2025 tax year is due for many business owners. This payment matters most for sole proprietors, partners, S-corporation shareholders, and others who receive business income without enough withholding.

January 20, 2026: Monthly sales and use tax for December 2025 is generally due. If your business collects local hospitality tax, plan for the same monthly rhythm: many South Carolina local governments require the prior month’s hospitality tax return and payment by the 20th. Moore Accounting Group recommends reconciling sales, exempt sales, tax collected, and hospitality-tax activity before the month closes—not on the 19th.

For employers, January is also the time to prepare year-end payroll forms. W-2 and certain 1099 deadlines may apply, so do not wait until tax-return season to organize contractor and employee records.

February and March 2026: Prepare Entity Returns

February 20, 2026: January sales and use tax is generally due, along with any applicable local hospitality tax filing for January. Businesses in the Lowcountry and Bluffton area that serve visitors, food, beverages, or lodging-related customers should make the 20th a recurring calendar reminder.

March 16, 2026: Calendar-year partnerships and S corporations must generally file their 2025 federal returns because March 15 falls on a Sunday in 2026. Partnerships file Form 1065, and S corporations file Form 1120-S. Both should provide owners with their Schedule K-1 information at that time. The key lesson for 2026 planning is simple: keep books current all year so the March 2027 filing season is not a scramble.

March 20, 2026: February sales and use tax and applicable local hospitality tax are generally due. Check the filing frequency assigned to your business; some businesses are approved to file quarterly or annually instead of monthly.

April 2026: Individual Filing and First 2026 Estimates

April 15, 2026: This is the deadline to file and pay 2025 federal and South Carolina individual income taxes for most calendar-year taxpayers, or to file an extension. It is also the first estimated-tax payment deadline for the 2026 tax year. For business owners, these are two separate items: one finishes the prior year, while the other helps pay tax as 2026 income is earned.

April 20, 2026: March sales and use tax and local hospitality tax are generally due. If your business is seasonal, do not assume a quieter month means no return is required. A zero return may still be required depending on your registration and filing status.

South Carolina generally expects estimated payments when you expect to owe at least $100 with your individual state return. Moore Accounting Group can help owners in Summerville, SC estimate both federal and state obligations from current profit instead of relying on last year’s income alone.

May Through September 2026: Keep the Monthly and Quarterly Rhythm

May 20, June 20, July 20, August 20, and September 21, 2026: Monthly sales and use tax is generally due on the 20th for the prior month. September’s deadline moves to Monday, September 21, because September 20 falls on a Sunday. Local hospitality tax commonly follows the same 20th-of-the-month schedule, but businesses should confirm the rule with the city or county that administers their tax.

June 15, 2026: The second federal and South Carolina estimated-tax payment is due.

September 15, 2026: The third federal and South Carolina estimated-tax payment is due.

These quarterly payments are not optional “extra” payments. They are part of the pay-as-you-go system for tax on income that is not covered by payroll withholding. Regular profit-and-loss reviews allow Moore Accounting Group to help Lowcountry and Bluffton area business owners adjust estimates when revenue, payroll, deductions, or owner draws change.

October Through December 2026: Plan Before Year-End

October 20, November 20, and December 21, 2026: Monthly sales and use tax returns for the prior month are generally due on the 20th. December’s date moves to Monday, December 21, because December 20 is a Sunday. The same timing is commonly used for local hospitality tax filings.

October is also a useful checkpoint for anyone who extended a prior-year individual return. More importantly, it is time to look ahead: review year-to-date profit, confirm bookkeeping is complete, identify major purchases, and estimate the January payment. Early planning gives business owners choices; last-minute planning usually only reveals a balance due.

January Through April 2027: The Final 2026 Deadlines

January 15, 2027: The fourth estimated federal and South Carolina income tax payment for 2026 is due for many calendar-year individuals.

March 15, 2027: Calendar-year partnerships and S corporations generally must file their 2026 returns and provide K-1 information to owners.

April 15, 2027: Calendar-year sole proprietors and other individual taxpayers generally file their 2026 federal and South Carolina income tax returns, pay any remaining balance, or request an extension to file. An extension gives more time to file, not more time to pay.

What If You Miss a Tax Deadline?

A missed deadline can lead to late-filing penalties, late-payment penalties, interest, or an estimated-tax underpayment penalty. The cost can grow over time, even when the original balance is manageable. If you miss a due date, file and pay as soon as possible, then get professional guidance on the next step rather than ignoring notices.

Early tax planning helps prevent these surprises. When Moore Accounting Group reviews your books, sales-tax activity, local hospitality-tax reporting, and estimated income tax throughout the year, you can set aside cash before a deadline arrives. For official rules and changes, review the IRS tax calendar, the South Carolina Department of Revenue’s 2026 estimated tax instructions, and its sales and use tax guidance.

Ready to replace deadline stress with a clear plan? Contact Moore Accounting Group to build a proactive tax filing schedule for your business in Summerville, SC, the Lowcountry, or the Bluffton area.