If you fail an IRS audit, the agency issues an examination report concluding you owe more tax, and you’re on the hook for that additional tax plus penalties that run from 20% to 75% of the underpayment and interest that compounds daily from the original due date of the return. That said, an audit finding isn’t the last word. You can appeal it, ask the IRS to waive the penalties, and arrange to pay the balance over time.
What Arrives in the Mail
When the audit closes, you’ll receive an examination report, usually Form 4549 (Income Tax Examination Changes), showing every adjustment the auditor made and the recalculated tax.1Internal Revenue Service. Audits by Mail – What to Do? Form 886-A comes with it and explains the reasoning behind each change.
Attached is a 30-day letter, typically Letter 525 or Letter 950. It gives you 30 days from the date on the letter to accept the changes or file a written protest.2Internal Revenue Service. Letters and Notices Offering an Appeal Opportunity Let the deadline pass and the IRS moves on to formal billing.
Signing Form 4549 and mailing it back with payment closes the case. It also waives your right to appeal. If you disagree with any part of the report, don’t sign.
What You’ll Actually Owe
Three separate charges stack up: the additional tax itself, penalties, and interest.
Accuracy-Related Penalty (20%)
The most common post-audit penalty adds 20% on top of the underpaid tax. The IRS applies it when you’ve been negligent or when your return contained a substantial understatement of income tax. An understatement is “substantial” if it’s more than 10% of the tax you should have reported, or $5,000, whichever is greater.3Office of the Law Revision Counsel. 26 USC 6662 Imposition of Accuracy-Related Penalty on Underpayments
Civil Fraud Penalty (75%)
If the IRS concludes any part of the underpayment was fraudulent rather than careless, the penalty jumps to 75% of the fraudulent portion. The IRS carries the initial burden of proving fraud, but once it establishes fraud on any piece of the underpayment, the whole underpayment is treated as fraud-related unless you can prove otherwise.4Office of the Law Revision Counsel. 26 USC 6663 Imposition of Fraud Penalty
Interest
Interest runs on both the unpaid tax and the penalties. It starts from the original due date of the return, not the date the audit concludes, and it compounds daily.5Office of the Law Revision Counsel. 26 USC 6601 Interest on Underpayment, Nonpayment, or Extensions of Time for Payment, of Tax6Office of the Law Revision Counsel. 26 USC 6622 Interest Compounded Daily The rate is set quarterly at the federal short-term rate plus three points. For the first quarter of 2026 the individual underpayment rate is 7%, dropping to 6% in the second quarter.7Internal Revenue Service. Quarterly Interest Rates An audit that took years to resolve can carry a heavy interest tail.
Getting Penalties Removed
The IRS will waive penalties in some situations, and this is one of the more overlooked moves after a bad audit result. Two paths exist.8Internal Revenue Service. Penalty Relief
First-Time Abatement
If you had a clean compliance record for the three tax years before the penalty year, the IRS may remove failure-to-file and failure-to-pay penalties under its First Time Abate program. You need to have filed all required returns for those three years and to have had no penalties in that period (or any earlier ones removed for a reason other than this same program).9Internal Revenue Service. Administrative Penalty Relief You can qualify more than once in a lifetime, as long as the clean three-year window in front of each new penalty is intact.
Reasonable Cause
Even without a clean record, the IRS may remove penalties if circumstances beyond your control kept you from complying. Fires, natural disasters, serious illness or a death in the immediate family, and inability to obtain necessary records all qualify. For accuracy-related penalties, the IRS also looks at how complex the issue was, the effort you made to report correctly, and whether you relied on a competent tax advisor after giving them the full picture.10Internal Revenue Service. Penalty Relief for Reasonable Cause A lack of funds by itself doesn’t qualify, though the reasons behind the shortage might.
Penalty relief removes only the penalties. The tax and interest still stand.
Fighting the Result
If you disagree with the audit, file a written protest within the 30-day window and request a conference with the IRS Independent Office of Appeals, which reviews cases separately from the examination division.11Internal Revenue Service. What to Expect from the Independent Office of Appeals The protest has to name the specific adjustments you dispute, explain your disagreement, and set out the facts and law backing your position.12Internal Revenue Service. 13Internal Revenue Service. Instructions for Form 2848
The 90-Day Letter
If Appeals doesn’t resolve it, the IRS issues a Notice of Deficiency, known as the 90-day letter. You have 90 days (150 if you’re outside the U.S.) to file a petition with the U.S. Tax Court.14Taxpayer Advocate Service. 90-Day Notice of Deficiency The filing fee is $60.15United States Tax Court. Court Fees
Miss those 90 days and the proposed deficiency becomes a final assessment. The IRS can then start collection (wage garnishment, bank levy) without giving you another chance to dispute the amount in court first. The deadline is hard; being a day late closes the door to Tax Court review of that assessment.
Paying What You Owe
Once the amount is final, whether by agreement or lost appeal, you have a balance due. Paying in full is cheapest because it stops interest. If you can’t, the IRS offers alternatives.
- Short-term payment plan. Up to 180 days to pay in full, no setup fee if you apply online, and in most cases no lien filed during that window.16Internal Revenue Service. Payment Plans Installment Agreements
- Long-term installment agreement. Monthly payments over a longer stretch. Interest and penalties keep accruing on the unpaid balance.
- Offer in Compromise. If paying in full would create genuine hardship, you can propose settling for less. The IRS weighs your income, expenses, and asset equity to decide whether your offer is roughly the most it could realistically collect. You must have filed all required returns and cannot be in open bankruptcy.17Internal Revenue Service. Offer in Compromise
Ignoring the debt is the worst option. Once you’ve been billed and haven’t paid, a federal tax lien attaches to all your property, including real estate, financial accounts, and personal assets.18Internal Revenue Service. Understanding a Federal Tax Lien A levy goes further and actually takes property: garnishing wages, emptying bank accounts, forcing the sale of assets.19Internal Revenue Service. Levy
If You Missed the Audit Entirely
Sometimes people fail an audit because they never engaged with it. Maybe the notices went to an old address, or the response window slipped by. Audit reconsideration lets you ask the IRS to reopen a closed audit when you have documentation that wasn’t part of the original examination. No special form is needed. A letter identifying what you’re disputing, with copies of your supporting records, sent to the office that last wrote to you, starts the process.20Taxpayer Advocate Service. Audit Reconsiderations
Reconsideration isn’t available if you signed a closing agreement, settled through an Offer in Compromise, or received a final Tax Court determination on the same issue. If you’ve already paid the full balance, the route is an amended return (Form 1040-X) claiming a refund. If you’re on an installment agreement while reconsideration is pending, keep paying until the IRS says otherwise.
Criminal Exposure Is Rare
Nearly all audits are civil matters and stay that way. Criminal cases are handled by a separate division, IRS Criminal Investigation, and are reserved for situations with strong evidence of willful wrongdoing.21Internal Revenue Service. Criminal Investigation (CI) at a Glance The bar is high: prosecutors must prove beyond a reasonable doubt that you intentionally violated a known legal duty. Tax evasion is a felony carrying up to five years in prison and a fine of up to $100,000 ($500,000 for corporations).22Office of the Law Revision Counsel. 26 USC 7201 Attempt to Evade or Defeat Tax Filing a fraudulent return carries up to three years and the same fines.23Office of the Law Revision Counsel. 26 USC 7206 Fraud and False Statements For taxpayers who made honest mistakes or claimed aggressive but good-faith deductions, criminal referral isn’t a realistic worry.
Don’t Forget Your State
A federal audit adjustment doesn’t stop at the federal line. Most states with an income tax require you to report changes to your federal return within a set period, often 60 to 180 days after the federal adjustment becomes final. Skip that step and you invite state penalties and interest on top of what you owe the IRS. Deadlines and procedures vary, so check with your state tax agency once the federal side is resolved.