How to Complete and File the Louisiana State Income Tax Return (IT-540)

To file your Louisiana state income tax return, use Form IT-540 if you were a full-year resident or Form IT-540B if you were a nonresident or part-year resident, and submit it by May 15, 2026, for the 2025 tax year. Louisiana now applies a flat 3 percent rate to taxable income, and you can file free through the state’s Louisiana Taxpayer Access Point (LaTAP) or mail a paper return to the Department of Revenue.¹²

Pick the Right Form

Your residency during the tax year decides which form you use. Full-year Louisiana residents who are required to file a federal return use Form IT-540.³ If you moved in or out of Louisiana during the year, or you lived elsewhere but earned income from Louisiana sources, file Form IT-540B. The IT-540B limits Louisiana’s tax to income tied to in-state activity or earned while you were physically present.⁴

Both forms are on the Department of Revenue’s forms page, and both can be completed through the state’s electronic filing portal.⁵

Gather Your Documents First

Have the following in front of you before you open the return:

Social Security numbers for you, your spouse if filing jointly, and any dependents.
W-2s from every employer, showing wages and Louisiana withholding.
1099s for freelance work, interest, dividends, retirement distributions, and any other non-wage income.
Your completed federal Form 1040. Louisiana uses your federal adjusted gross income (AGI) as the starting point for the state calculation.⁶
Receipts and records for any deductions and credits you plan to claim.

Copy your federal AGI onto the state return exactly as it appears on the 1040. A mismatch between the two figures is a common trigger for automated review or a follow-up letter from the Department of Revenue.

How Louisiana Calculates the Tax

For the 2025 tax year and later, Louisiana replaced its old graduated brackets (1.85, 3.50, and 4.25 percent) with a single flat rate. Everyone pays 3 percent of Louisiana taxable income. On the return, you multiply that figure by 0.03.¹

The reform also nearly tripled the standard deduction, which replaced the old combined personal exemption and standard deduction:⁷

Single or married filing separately: $12,500.
Married filing jointly, qualifying surviving spouse, or head of household: $25,000.

A married couple filing jointly owes no Louisiana income tax on the first $25,000 of income.

Deductions and Credits Worth Checking

School Expense Deduction

Louisiana residents can deduct up to $6,000 per dependent for education costs. For a child in nonpublic school, you deduct actual tuition paid up to that cap. For a child in public school or being homeschooled, the deduction is 50 percent of qualifying costs, still capped at $6,000. The student must be claimed as your dependent on your current or prior-year return, and you need to keep receipts. Report the deduction on Schedule E of the IT-540 and attach the Louisiana School Expense Deduction Worksheet.⁸

Other Credits

Louisiana offers a credit for taxes paid to other states (which prevents double taxation on income earned across state lines), a child care credit, and an earned income credit. Each has its own eligibility rules and supporting schedule, listed in the return instructions.

How to Submit the Return

Electronic Filing Through LaTAP

The state’s electronic filing system is the Louisiana Taxpayer Access Point at latap.revenue.louisiana.gov. Individual income tax returns for tax year 2022 and later can be filed there free of charge.⁹ If you used the older Louisiana File Online system, your account does not carry over. Register a new LaTAP account. E-filed returns tend to process faster and produce fewer keying errors than paper.

Paper Filing

If you file by mail, the address depends on whether money is changing hands:

Refund or zero balance: Louisiana Department of Revenue, P.O. Box 3440, Baton Rouge, LA 70821-3440.
Payment enclosed: Louisiana Department of Revenue, P.O. Box 3550, Baton Rouge, LA 70821-3550.

Make the check or money order payable to the Louisiana Department of Revenue and include the appropriate payment voucher.¹⁰

If You Need More Time

Louisiana grants an automatic six-month extension without any paperwork. For 2025 returns, that pushes the filing deadline from May 15, 2026, to November 16, 2026.¹¹

The extension covers filing only. It does not push back payment. If you expect to owe, send what you owe with payment voucher Form R-2868V by May 15, or interest and the late-payment penalty start running that day regardless of your filing extension.

If You Cannot Pay in Full

The Department of Revenue offers monthly installment agreements with a minimum term of six months. Approval requires a 20 percent down payment on the balance and a non-refundable $105 application fee. The fee is waived if your Louisiana adjusted gross income on your most recently filed return is $25,000 or less. All installment payments come through automatic bank debit.¹²

Apply through LaTAP, by emailing Form R-19026 to collection.inquiries@la.gov, or by mailing it to the Collection Division at P.O. Box 66658, Baton Rouge, LA 70896-6658. Do not send the installment request with your tax return. Missing a payment, or falling behind on other state tax obligations, defaults the agreement and makes the full balance due at once. Reinstatement costs $60, or $105 if the agreement has been cancelled for 90 days or more. The state may also file a tax lien if your balance exceeds $2,500 or the payment schedule runs longer than 12 months.¹²

After You File

Tracking Your Refund

Use the “Where’s My Refund?” tool on the Department of Revenue website. You will need your Social Security number and the refund amount you expect. Electronic returns are typically processed within four weeks; paper returns take up to eight.¹³

Identity Verification

If your return is flagged for identity verification, you will receive a letter directing you to complete an online quiz. The quiz uses the name listed first on the letter, and you need the last four digits of the primary taxpayer’s SSN plus the Letter ID number. Once you pass, e-filed returns take up to 60 days to process; paper returns take 12 to 14 weeks. If you cannot pass the quiz, the Department will ask for copies of your federal return, wage statements, a photo ID, and the verification letter, sent to P.O. Box 3929, Baton Rouge, LA 70821-3929, by fax to 225-231-6204, or by email to IDVerification@la.gov.¹⁴

Amending a Return

If you find an error, file a corrected return using the same form you originally used. Mark the “Amended Return” box, complete the form as if the original had never been filed, and attach a written explanation along with a copy of your federal amended return (Form 1040-X) if one exists. Do not adjust for refunds already received or payments already made; the Department reconciles the account. Mail an amended return to P.O. Box 3550 if you owe more, or P.O. Box 3440 otherwise, or file it through LaTAP. The refund claim deadline on an amended return is three years from December 31 of the year the tax became due, or one year from the date you paid, whichever is later.¹⁰¹⁵

What Happens If You File or Pay Late

Late filing and late payment are separate penalties. The late-filing penalty is 5 percent of the tax owed for the first 30 days, plus another 5 percent for every additional 30-day period or fraction of one, capped at 25 percent of the tax due.¹⁶ Interest accrues on any unpaid balance at a rate set annually by the state.¹⁷ The automatic six-month extension protects you from the late-filing penalty as long as you file by November 16, but it does nothing to stop the late-payment penalty or interest, both of which run from May 15 on any unpaid tax.

Quarterly Estimated Payments

If you expect to owe more than $1,000 ($2,000 for joint filers) after withholding and credits, you owe quarterly estimated tax during the year. Calendar-year deadlines are April 15, June 15, September 15, and January 15 of the following year. You can pay the full estimate with the first installment or spread it across the four dates.

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Louisiana Department of Revenue. What Are the Individual Income Tax Rates and Brackets?
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Louisiana Department of Revenue. Individual Income
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Louisiana Department of Revenue. Individual Income Tax
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Louisiana Department of Revenue. 2025 IT-540B Instructions
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Louisiana Department of Revenue. Tax Forms for Individuals
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Louisiana State Legislature. Louisiana Code 47:293 – Definitions
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Louisiana Department of Revenue. Are There Any Changes to the Combined Personal Exemption Standard Deduction?
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Louisiana Department of Revenue. School Expense Deduction
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Louisiana Department of Revenue. Individual Income Online Tax Filing
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Louisiana Department of Revenue. How Can I File an Amended Return?
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Louisiana Department of Revenue. Louisiana State Income Tax Deadline Is May 15
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Louisiana Department of Revenue. Installment Request for Individual Income
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Louisiana Department of Revenue. Where’s My Refund?
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Louisiana Department of Revenue. Identity Verification Quiz
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Louisiana State Legislature. Louisiana Code 47:1623 – Prescription of Refunds or Credits
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Louisiana State Legislature. Louisiana Code 47:1602 – Penalty for Failure to Make Timely Return
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Louisiana Department of Revenue. Penalties