Louisiana runs a month behind the federal calendar across the board. For the 2025 tax year, individual, C-corporation, S-corporation, and partnership returns are all due May 15, 2026, the 15th day of the fifth month. That uniform May date, not the federal April or March dates, is what a multistate workflow has to track for Louisiana. The 2025 year also brings a new flat individual rate.

What are Louisiana's 2026 tax filing deadlines?

For the 2025 tax year, the Louisiana individual return (IT-540), the corporation income and franchise return (CIFT-620), and the partnership return (IT-565) are all due May 15, 2026. Louisiana sets these at the 15th day of the fifth month, so pass-throughs do not follow the federal March date and individuals do not follow the federal April date.

How does Louisiana's extension work?

Louisiana grants an automatic six-month extension to file, with no request required. For 2025 returns the extended date is November 16, 2026 (the statutory November 15 falls on a Sunday). The extension covers filing only. Tax remains due May 15, 2026, and interest and penalty run on anything unpaid after that date.

What changed with Louisiana's 2025 tax rates?

Louisiana moved to flat rates effective January 1, 2025. The individual income tax is now a flat 3%, replacing the old graduated brackets, and the corporation income tax is a flat 5.5%. The standard deduction rose alongside the rate change. The corporate franchise tax is repealed for franchise periods beginning on or after January 1, 2026, which makes the 2025 cycle the wind-down for most filers.

What is Louisiana's pass-through entity (PTE) election?

Louisiana lets an S-corporation or a partnership elect to be taxed as if it were a C-corporation, which moves the state tax deduction above the federal SALT cap. The election is available for 2025, made on Form R-6980, with Form R-6981 reporting items that stay taxable to the owners. For periods beginning on or after January 1, 2025, the electing-entity rate is a flat 3%, tracking the individual rate.

Who owes Louisiana estimated tax?

Individuals expecting to owe more than $1,000 (single) or $2,000 (joint) in Louisiana tax pay quarterly on April 15, June 15, September 15, 2026, and January 15, 2027 (Form IT-540ES). Partnerships with nonresident individual partners generally must file a composite return (Form R-6922) for those partners unless an exception applies.

How does a firm handle Louisiana at scale?

The single thing to get right is the date. Louisiana puts every major return on May 15, so a workflow keyed to federal April and March deadlines will mis-date the entire Louisiana book. Set the May 15 filing date and the November 16 extension date as Louisiana-specific, fold the new 3% flat rate into planning, and the state stops being an exception that gets missed. See how we think about scaling tax prep workflows.

Where do these dates come from?

All deadlines and thresholds here trace to the Louisiana Department of Revenue. Verify against the source before filing.