You can amend a tax return during an audit, and in most cases the IRS examiner assigned to your case is required to consider the corrections you submit. The Internal Revenue Manual directs examiners to take amended returns into account for any year under active examination, though the delivery method and timing matter more than they would for a routine amendment filed outside an audit.
The Examiner Has to Consider Your Amendment
The IRS’s own procedures are more favorable to taxpayers here than many people assume. The Internal Revenue Manual states that examiners “must take into consideration an amended return filed for a year under examination,” and that any amended return received during an examination “must remain with the case file.”1Internal Revenue Service. IRM 4.10.11 Claims for Refund, Requests for Abatement, and Audit Reconsideration If your amendment claims a refund, the examiner generally has to expand the scope of the audit to address the refund issues you raised.
The examiner’s discretion to disregard your corrections is narrow. The IRM allows it only in “rare instances” where doing so serves the IRS’s interest in determining the deficiency, and the examples given are returns with multiple math errors or fraud.1Internal Revenue Service. IRM 4.10.11 Claims for Refund, Requests for Abatement, and Audit Reconsideration Outside those situations, your corrected figures become part of the examination. A separate IRM provision confirms that amended returns received during examination “will be examined to determine whether the tax reported is correct” and the review happens “as soon as possible after the return is received.”2Internal Revenue Service. IRM 4.10.8 Report Writing
The examiner may formally process your Form 1040-X as a separate filing, or fold the corrected numbers directly into the audit without running the 1040-X through the standard pipeline. Either way, the changes get evaluated.
Related Corrections vs. Unrelated Ones
How you submit the amendment depends on whether your correction overlaps with what the IRS is already looking at.
If the error is unrelated to the audit topics, prepare and submit a standard Form 1040-X. Say the IRS is reviewing your business deductions and you realize you forgot to claim an education credit. That credit is a separate issue. Prepare the 1040-X for the missed credit and give it to the examiner handling your case so it stays with the file.
If the error falls squarely within what the IRS is already auditing, filing a formal 1040-X through normal channels creates confusion. Say the audit is about unreported income and you want to disclose additional income you missed. Prepare the corrected information with full documentation and hand it directly to the examiner, who will incorporate it into the audit report. That path is cleaner and faster because the examiner is already working those same numbers.
Preparing the Amendment
Whether you file a formal 1040-X or give corrected information straight to the examiner, you need the same supporting materials: your original return, the audit notice so you can reference the specific issues under examination, and documentation backing every change. That includes corrected W-2s, additional 1099s, receipts for deductions you missed, or records showing income you need to report.
Form 1040-X is the standard vehicle for individual amendments. You can file it electronically for the current year or the two prior tax years, or submit it on paper.3Internal Revenue Service. About Form 1040-X, Amended U.S. Individual Income Tax Return The form uses three columns: the original figures, the net change, and the corrected figures. Part II asks you to explain each change.4Internal Revenue Service. Instructions for Form 1040-X Be specific. “Correcting an error” tells the examiner nothing. “Reporting $8,200 in freelance income from Client X that was omitted from the original return” tells them everything they need.
When your return is under audit, deliver the completed 1040-X and all supporting documents directly to the assigned examiner instead of mailing them to a processing center. Hand them over at a scheduled meeting or mail them to the address the examiner provided in their correspondence. That keeps everything in one place and prevents your amendment from drifting through normal processing while your case is open.
Watch the Statute of Limitations
The IRS generally has three years from the date you filed your original return to assess additional tax.5Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection Filing an amended return during an audit can extend that window under a specific rule.
If the IRS receives a signed document showing you owe additional tax within the last 60 days of the normal assessment period, the IRS gets an extra 60 days from the date it receives the document to assess the additional amount.5Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection A signed 1040-X showing more tax owed qualifies. The statute does not restart entirely; it extends only by those additional days. If your amended return reduces what you owe or claims a refund, this extension does not apply.
This matters most when an audit is dragging on near the three-year mark. If your amendment increases your liability and you submit it in that final 60-day window, you have effectively given the IRS more time to work. That is not a reason to delay, because concealing an error carries much worse consequences, but the timing is worth understanding.
Interest and Penalties on the Additional Tax
Submitting an amended return does not pause or end the audit. The examiner reviews your changes, verifies the documentation, and decides whether the corrected figures hold up. If they agree, your numbers go into the final audit report. That report may show additional tax, a reduced liability, or a refund, though a refund is typically held until the audit closes.
Interest
If the amendment shows you owe more, interest runs from the original due date of the return, not from the date you file the amendment. For Q1 2026, the IRS charges 7% per year on individual underpayments, compounded daily.6Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The IRS adjusts this rate quarterly. Interest accrues by statute and is not negotiable.
Accuracy-Related Penalty
The standard accuracy-related penalty is 20% of the underpayment caused by negligence, disregard of rules, or a substantial understatement of income tax.7Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments A substantial understatement means you understated your tax by the greater of 10% of the correct tax or $5,000. If your amendment increases what you owe, this penalty is on the table.
The tax code provides a full defense: no accuracy-related penalty applies if you show reasonable cause for the error and that you acted in good faith.8Office of the Law Revision Counsel. 26 USC 6664 – Definitions and Special Rules Voluntarily correcting an error, especially before the IRS discovers it during the audit, is strong evidence of good faith. If you catch the mistake yourself and bring it to the examiner with full documentation, you are in a much better position to argue reasonable cause than if the examiner finds it first.
Why Voluntary Correction Helps
Coming forward during an audit signals cooperation. The examiner still has to verify your numbers, but the penalty analysis shifts meaningfully in your favor when you raise the issue yourself. Waiting for the examiner to uncover the same error makes it much harder to argue against negligence. If the IRS determines the underpayment was fraudulent rather than negligent, the penalty jumps to 75% of the underpayment.
Tell Your State Too
Federal audit changes almost always affect your state return, and most states require you to report federal adjustments to their revenue department. There is no uniform national rule. Deadlines range from 30 days to two years depending on the state, and the required format varies from filing an amended state return to simply submitting a letter. Some states want notification when the audit begins; others trigger the requirement only when you sign the final agreement with the IRS. Failing to notify your state can result in penalties, interest, and lost refund opportunities. Check your state revenue department’s website for specific requirements as soon as you know your federal return is being adjusted.
If You Disagree With the Final Report
Once the examiner finishes reviewing everything, including any amendments, you receive a report with proposed changes. If you disagree, ask first for an informal conference with the examiner’s manager. It costs nothing and sometimes resolves the dispute. If that does not work, the IRS will send a 30-day letter proposing adjustments and giving you 30 days to request a conference with the IRS Independent Office of Appeals.9Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond For proposed adjustments of $25,000 or less, you can use Form 12203, Request for Appeals Review, a one-page form.10Internal Revenue Service. Form 12203, Request for Appeals Review Larger amounts require a formal written protest.
If you have a right you feel the examiner is ignoring, such as the right to submit documentation and have it considered, you can raise it directly or through a representative. You can be represented by an attorney, CPA, or enrolled agent at any point in the audit or appeals process.11Internal Revenue Service. Taxpayer Bill of Rights If normal IRS channels are not working, the Taxpayer Advocate Service exists to help.