Iowa tax penalties at a glance

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

Late-Filing Penalty
5% of the unpaid tax (applies if under 90% of the correct tax was paid by the due date)
Late-Payment Penalty
5% of the unpaid tax (failure to timely pay; applies if under 90% paid by the due date)
Interest on Unpaid Tax
10% per year / 0.8% per month (2026)
State Tax Authority
Iowa Department of Revenue
State DOR Phone
(800) 367-3388

Source: Iowa 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 Iowa penalty waived

Submit a Penalty Waiver Request (Form 78-629) or request via GovConnectIowa; waivers are limited to the grounds in Iowa Code section 421.27.

— Iowa vs. Federal —

Most people who owe a Iowa 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 Iowa 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 Iowa, federal abatement requests are processed through the IRS service center in Kansas City, MO.

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
Kansas City, MO
Authorization Form
Form 8821 (Tax Info Auth)
Typical IRS Processing
60–120 days

What our practice does for Iowa 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 Iowa 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 Kansas City, MO 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.