Tax Deadline Calendar
The dates below are the federal deadlines for calendar-year filers. When a deadline falls on a Saturday, Sunday or legal holiday it moves to the next business day, and the IRS occasionally postpones deadlines for federally declared disaster areas — South Carolina has had several. Always confirm the current year's date on IRS.gov before relying on it.
South Carolina individual and business return deadlines generally follow the federal dates, and South Carolina estimated payments follow the federal quarterly schedule. Confirm state specifics with the South Carolina Department of Revenue.
Autumn 2026
15 September 2026
Q3 2026 estimated tax payment
Individuals, sole proprietors, and pass-through owners
Third-quarter estimated payment for the 2026 tax year.
15 September 2026
Extended partnership and S corporation returns
Calendar-year partnerships and S corporations
Final deadline for 2025 Forms 1065 and 1120-S that were extended in March. K-1s issued to owners come out of this filing.
15 October 2026
Extended individual returns
Individuals who filed an extension
Final deadline for the 2025 Form 1040. The extension extended the time to file, not the time to pay — interest has been running since April on anything unpaid.
15 October 2026
Extended C corporation returns
Calendar-year C corporations
Final deadline for extended 2025 Forms 1120.
Year end 2026
31 December 2026
Most planning options close
Everyone
Entity elections, timing of income and deductions, charitable gifts, and most retirement plan actions have to be executed inside the tax year. After this date the 2026 return largely reports a settled set of facts.
Winter 2027
15 January 2027
Q4 2026 estimated tax payment
Individuals, sole proprietors, and pass-through owners
Final estimated payment for the 2026 tax year.
1 February 2027
W-2 and 1099-NEC deadline
Employers and businesses that paid contractors
Forms must be furnished to recipients and filed. The statutory date is 31 January, which falls on a Sunday in 2027, so it moves to the next business day.
Filing season 2027
15 March 2027
Partnership and S corporation returns
Calendar-year partnerships and S corporations
Forms 1065 and 1120-S for the 2026 tax year, or an extension to 15 September. Owners cannot finish a personal return until the K-1 arrives, so this date drives the next one.
15 April 2027
Individual and C corporation returns
Individuals and calendar-year C corporations
Forms 1040 and 1120 for the 2026 tax year, or an extension to 15 October. Tax owed is due on this date regardless of any extension.
15 April 2027
Q1 2027 estimated tax payment
Individuals, sole proprietors, and pass-through owners
First estimated payment for the 2027 tax year — due the same day last year's balance is.
15 April 2027
IRA and HSA contributions for 2026
Individuals
One of the few items that can still be done after the tax year has closed.
Rest of 2027
15 June 2027
Q2 2027 estimated tax payment
Individuals, sole proprietors, and pass-through owners
Second estimated payment for the 2027 tax year.
15 September 2027
Q3 2027 estimate and extended pass-through returns
Individuals and calendar-year partnerships and S corporations
Third estimated payment for 2027, and the final deadline for extended 2026 Forms 1065 and 1120-S.
15 October 2027
Extended individual and C corporation returns
Individuals and C corporations who filed an extension
Final deadline for extended 2026 Forms 1040 and 1120.
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.
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