Louisiana calendar and forms

Louisiana runs its own calendar. The return is due May 15, a month after the federal return, which in 2027 falls on a Saturday, so expect Monday, May 17, 2027. The four estimated payments fall on April 15, June 15, September 15 and January 15, the same as the federal dates. The extension is automatic, six months to November 15, 2027, with no form to file, and it extends nothing but the paperwork: tax not paid by the May due date draws interest and a late-payment penalty from that day. There is one return for residents, Form IT-540, one for part-year residents and nonresidents, Form IT-540B, and a single Schedule E that carries nearly every Louisiana adjustment.

Because the return starts from federal adjusted gross income and has no itemized deductions of its own, most Louisiana filers touch two pages: the IT-540 itself and Schedule E, where exempt income such as Social Security, government pensions, START 529 deposits and school expenses is listed by code. The credit schedules, the nonresident return and the estimated-tax forms are for people who moved, who have children in child care, who owe estimates, or who want to fix a return already filed.

The 2027 filing season, dated

How the extension really works

Under R.S. 47:103, every individual gets an automatic six-month extension of time to file for tax years 2022 and later. There is no form, paper or electronic, and no request. What the extension does not do is extend the time to pay. Interest and the late-payment penalty run from the May due date on whatever was not paid by then. Anyone who expects to owe should send the expected balance by May 17 through LaTAP, the Department’s online system, or by check with a payment voucher, and file the return when it is ready. If the estimate was too high, the excess comes back as a refund; if too low, penalty and interest run only on the shortfall.

Estimated payments

Louisiana requires estimated payments when the expected tax after credits and withholding is more than $1,000 on a single return or $2,000 on a joint return. For 2026 and later, Act 307 of 2026 sets each installment at 25% of the lesser of 70% of the current year’s tax or 100% of last year’s; through 2025 the current-year figure was 90%. The underpayment penalty is 12% a year, figured on Form R-210R for residents and R-210NR for nonresidents, and the underpayment period now ends on the May due date. The annualized-income method is gone. Farmers and fishermen with two-thirds of their income from farming or fishing may pay once by January 15, or file and pay by March 1, without penalty. The Department’s individual income tax page still described the 90% rule when this was written; the 2026 statute controls.

Because Social Security and government pensions are exempt and most wage earners are over-withheld at 3.09%, the people most often caught are the self-employed, landlords, owners of pass-through businesses, anyone with a large capital gain (there is no Louisiana withholding on gains) and a retiree under 65 drawing on an IRA with no state withholding.

The forms, in the order a filer meets them

Filing, paying and checking a refund

Louisiana File Online, the Department’s free web filing application at latap.revenue.louisiana.gov, files original and amended IT-540 returns, takes estimated and balance-due payments by bank debit, and shows refund status. It is the state’s own system and does not file the federal return. The IT-540B can be filed there too, but not by a first-time filer. Commercial software e-files both returns with the federal one. Paper returns go to P.O. Box 3440, Baton Rouge, LA 70821-3440, or P.O. Box 3550, Baton Rouge, LA 70821-3550 if a payment is enclosed.

The Department says an error-free e-filed return is refunded in about four weeks, a paper return in about eight. Two things slow it down. First-time Louisiana filers get a paper check no matter how they asked to be paid. And some returns are held for an Identity Verification Quiz: a letter arrives with a Letter ID, the quiz is taken online using the last four digits of the primary filer’s Social Security number, the Letter ID and last year’s Louisiana return, and once it is passed, processing takes up to 60 days for an e-filed return or 12 to 14 weeks for paper. Calling does not speed up a refund; the “Where’s My Refund” link on LaTAP shows the same status the agent sees.

The Department’s headquarters is at 617 North Third Street, Baton Rouge, LA 70802, open 8:00 to 4:30 Monday through Friday, with regional offices in New Orleans, Lafayette, Alexandria, Monroe, Shreveport and Lake Charles. The main phone number is 855-307-3893.