Louisiana tax penalties at a glance

When you file or pay Louisiana taxes late, the Louisiana Department of Revenue adds a penalty and charges interest on the unpaid balance. These state penalties are assessed under Louisiana law and are entirely separate from any federal IRS penalty on your federal return.

Late-Filing Penalty
5% of tax due per 30 days, up to a maximum of 25%
Late-Payment Penalty
0.5% of unpaid tax per 30 days, up to a maximum of 25% (individual income tax)
Interest on Unpaid Tax
10.5% per year (2026)
State Tax Authority
Louisiana Department of Revenue
State DOR Phone
(855) 307-3893

Source: Louisiana Department of Revenue (official guidance). Penalty caps and interest rates change — several states reset interest quarterly — so verify the current figure before relying on it.

Getting a Louisiana penalty waived

Delinquency penalties may be waived (R.S. 47:1603) for reasonable cause rather than negligence; request via the Request for Waiver of Penalties for Delinquency.

Louisiana vs. Federal

Most people who owe a Louisiana penalty also owe a federal IRS penalty — and the federal one is usually larger. The good news: federal penalties can often be removed entirely through first-time abatement or reasonable cause. That is the part our practice handles.

The federal side: IRS penalties & Form 843

The IRS does not assess penalties differently in Louisiana than anywhere else — failure-to-file, failure-to-pay, and failure-to-deposit penalties are governed by federal law and apply uniformly nationwide. What changes by state is the IRS service center your case routes through. For Louisiana, federal abatement requests are processed through the IRS service center in Memphis, TN.

The mechanism is the same everywhere: Form 843, mailed with substantiation. The legal grounds are first-time penalty abatement, reasonable cause, statutory exception, or administrative waiver. When abatement is granted, the IRS refunds the penalty and the interest it charged on that penalty.

Federal Form for Abatement
Form 843 (mailed)
IRS Service Center
Memphis, TN
Authorization Form
Form 8821 (Tax Info Auth)
Typical IRS Processing
60–120 days

What our practice does for Louisiana taxpayers

We represent clients in all 50 states under IRS Circular 230 authorization. Because federal abatement is state-agnostic, location is rarely a constraint. For Louisiana clients specifically, we pull your IRS transcripts (via Form 8821), confirm exactly which penalties were assessed and for which periods, route Form 843 to the Memphis, TN service center, and build the reasonable-cause substantiation. The work is contingency-based: if we do not recover, you do not pay.

Start with the calculator on this page — enter your name, email, and rough penalty and interest amounts. We return a refund estimate within one business day and, if you choose to proceed, send the Form 8821 authorization for signature.