Business Tax Deadlines

State filing information

Mississippi

Business tax filing in Mississippi: state returns, sales tax, other business taxes, and the federal dates that apply everywhere.

checked 2026-09-01Verified against Mississippi Department of Revenue (Income and Franchise Tax Bureau). 8 sources.

Corporate income tax return

April 15
The Mississippi combination return of corporate income and franchise tax (Form 83-105) must be filed on or before the 15th day of the 4th month...

Partnership / S corporation returns

March 15
Partnerships March 15; Same for S corporations

Sales tax return

20th of the following month
sales and use tax · Based on the annual amount of tax remitted to DOR

Other business taxes

1 tax
Corporation franchise tax (being phased out; repealed effective Jan 1, 2028 under SB 2858 of 2016)

Mississippi Department of Revenue

Other business taxes

TaxWho owes itDue
Corporation franchise tax (being phased out; repealed effective Jan 1, 2028 under SB 2858 of 2016)Every corporation, including S corporations, domesticated or qualified to do business in Mississippi, on capital employed in Mississippi in excess of $100,000With the combination return: 15th day of the 4th month after year end for C corporations...

Rules in full

Corporate income tax

The Mississippi combination return of corporate income and franchise tax (Form 83-105) must be filed on or before the 15th day of the 4th month following the close of the accounting year. Income tax rates: 0% on first $5,000, 4% on next $5,000, 5% over $10,000.

Extension. Mississippi follows federal filing and extended due dates; to obtain the extension, remit any tax due with Form 83-180...

Partnerships and S corporations

S corporations are not subject to Mississippi income tax at the entity level but every S corporation domesticated or qualified in Mississippi IS subject to the franchise tax levy (reported on Form 84-105) through tax year 2027. Pass-through entities may make the electing pass-through entity (PTE) election to pay income tax at the entity level (covered in the 84-100 instructions). Nonresident-owner withholding/composite rules apply. Electronic filing is mandated for entities with assets of $250,000 or more or 100 or more K-1s.

Sales and use tax

Due date. Returns are due on or before the 20th day following the end of the reporting period (next business day if a weekend or holiday).

Filing frequency. Based on the annual amount of tax remitted to DOR.

Thresholds. Annual: less than $600 per year. Quarterly: $600 to $3,599 per year. Monthly: more than $3,599 (i.e. $3,600 or more) per year.

Notes

Mississippi files income and franchise tax on one combination return. The franchise tax rate steps down each year through 2027 and is repealed for 2028. Timely-filer sales tax discount of 2% (capped $50 per period, $600 per year). Annual reports are filed with the Secretary of State and are not covered here.

What we could not confirm. A June accelerated sales tax payment requirement for large Mississippi taxpayers has been reported elsewhere but appears nowhere on the DOR reporting-requirements page fetched, so prepayment is left null. Corporate income tax rate schedule and franchise rates were confirmed on two DOR sources; the exact form number for the electing PTE schedule was not extracted.

Active IRS disaster relief in Mississippi

Taxpayers in the declared areas below have federal deadlines postponed. The IRS release governs who qualifies.

  1. NOV2Mon
    Mississippi
    Severe storms, straight-line winds, tornadoes and flooding in the State of Mississippi
    Postponed to
  2. FEB1Mon
    Mississippi
    Tropical Storm Arthur in Mississippi
    Postponed to

All active postponements

Federal dates that apply in Mississippi

  1. SEP15Tue
    Individuals & Sole Proprietors
    Q3 2026 estimated tax payment (Form 1040-ES)
  2. SEP15Tue
    Partnerships
    Form 1065 extended return (Form 7004), tax year 2025
  3. SEP15Tue
    S-Corporations
    Form 1120-S extended return (Form 7004), tax year 2025
  4. SEP15Tue
    C-Corporations
    Q3 2026 corporate estimated tax (Form 1120-W)
  5. OCT15Thu
    Individuals & Sole Proprietors
    Form 1040 extended return (Form 4868), tax year 2025
  6. OCT15Thu
    C-Corporations
    Form 1120 extended return (Form 7004), tax year 2025

All 2026 federal deadlines

Sources

  1. https://www.dor.ms.gov/business/corporate-income-and-franchise-tax official
  2. https://www.dor.ms.gov/ official
  3. https://www.dor.ms.gov/business/corporate-income-and-franchise-tax-faqs official
  4. https://www.dor.ms.gov/sites/default/files/tax-forms/business/2025%20CIT%20INSTRUCTIONS%2083-100%20-%20Final%20%2001.14.2026.pdf official
  5. https://www.dor.ms.gov/sites/default/files/tax-forms/business/2025%20PTE%20INSTRUCTIONS%2084-100%20-%20Final%20%2001.14.2026.pdf official
  6. https://www.dor.ms.gov/business/sales-use-tax/reporting-requirements official
  7. https://www.discern.com/resources/mississippi-franchise-tax-information
  8. https://www.avalara.com/us/en/taxrates/state-rates/mississippi/mississippi-sales-tax-guide.html

Checked 2026-09-01; researcher confidence 0.90. Corrections with a link to the state's own page: contact@businesstaxdeadlines.com.