Every IRS examination runs on a chain of tax audit deadlines, starting with the three years the IRS generally has from the date you filed to open an audit at all. Once one begins, you typically have 30 days to respond to the opening letter, a document deadline set by the examiner, 30 days to appeal the results, 90 days to petition the U.S. Tax Court, and 21 days to pay any balance the IRS assesses. Miss any of these and your options narrow quickly.
How Long the IRS Has to Start an Audit
The clock starts the day you file. Under federal law, the IRS generally has three years from that filing date to assess additional tax.1Office of the Law Revision Counsel. 26 U.S.C. 6501 – Limitations on Assessment and Collection File early and the countdown still doesn’t start until the original due date. A return filed in February for a tax year with an April 15 deadline triggers the three-year period on April 15, not the earlier filing date.
Two situations stretch that window. If you omit more than 25 percent of your gross income, the period doubles to six years. The same six-year period applies if you fail to report certain foreign financial assets worth more than $5,000.1Office of the Law Revision Counsel. 26 U.S.C. 6501 – Limitations on Assessment and Collection And if you file a fraudulent return or never file at all, there is no time limit; the IRS can come after you decades later.2Office of the Law Revision Counsel. 26 U.S.C. 6501 – Limitations on Assessment and Collection
When the IRS Asks You to Extend the Window
As the three- or six-year deadline approaches, the IRS will often ask you to sign Form 872, which extends the assessment period by mutual agreement.3Internal Revenue Service. IRM 25.6.22 – Extension of Assessment Statute of Limitations by Consent Form 872-A keeps the window open indefinitely until either side terminates it.
You are not legally required to sign. But refusing usually backfires: if the examiner can’t finish before the statute expires, the IRS typically issues an assessment based on whatever it already has, and that is almost always worse than the outcome cooperation would produce. Signing preserves your ability to keep supplying documentation and negotiating.
Responding to the Opening Audit Letter
The audit itself starts with a letter. In a correspondence audit, the IRS sends Letter 525, a 30-day letter explaining the proposed changes to your return.4Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond In a field audit, a separate notification letter comes first. Either way, a deadline is printed directly on the notice.
You generally have 30 days from the date on the letter to respond.4Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond Need more time? Contact the examiner listed on the notice before the deadline expires. The IRS doesn’t publish a maximum extension, but examiners have discretion to grant additional time when you explain why you need it.5Internal Revenue Service. IRS Audits
Ignoring the 30-day deadline doesn’t make the audit go away. The IRS simply proceeds with the data it already has, which usually means disallowing deductions and credits you claimed. The examiner will not chase you.
Producing Documents on the Examiner’s Timeline
Once you’re in contact, the examiner sends Form 4564, the Information Document Request (IDR), listing the specific records needed to verify what you reported — bank statements, receipts, mileage logs, contracts, and the like.6Internal Revenue Service. Form 4564 – Information Document Request
There is no statutory deadline for an IDR. The due date is set by the examiner and printed on the form. It depends on the complexity of the request and the volume of records involved. Five years of bank statements across multiple accounts will draw more time than a short list of receipts.
Keep copies of everything you send, and keep the originals. If you mail paper documents, the postmark date counts as the filing date, not the date the IRS opens the envelope.7Office of the Law Revision Counsel. 26 U.S. Code 7502 – Timely Mailing Treated as Timely Filing Certified mail with a return receipt protects you if the timing is ever disputed. The IRS Document Upload Tool provides confirmation of receipt and avoids mailing risk entirely.8Internal Revenue Service. IRS Document Upload Tool Failing to produce requested records voluntarily can lead the examiner to issue a formal summons.
Appealing the Results
If you disagree with what the examiner found, two layers of review are available, each with a firm deadline.
30 Days to Request an Appeals Conference
After the examination concludes, the IRS sends an examination report, often with a 30-day letter, explaining the proposed changes. You have 30 days from the date of that letter to file a written protest and request a conference with the IRS Independent Office of Appeals.9Internal Revenue Service. Preparing a Request for Appeals Appeals officers are independent of the examination division, and many disputes resolve at this stage.
If the total proposed additional tax and penalties for each tax period is $25,000 or less, you can file a Small Case Request instead of a formal protest — a brief letter identifying the items you disagree with and why.9Internal Revenue Service. Preparing a Request for Appeals Amounts above $25,000 require a full written protest with a statement of facts, the law you rely on, and your supporting arguments.
90 Days to Petition the Tax Court
If the Appeals conference doesn’t resolve things, or if you skip Appeals, the IRS issues a Statutory Notice of Deficiency, commonly called a 90-day letter. You have exactly 90 days from the mailing date, or 150 days if the notice is addressed to you outside the United States, to file a petition with the U.S. Tax Court.10Taxpayer Advocate Service. Letter 3219, Notice of Deficiency
This is the deadline that matters most. Miss it and the IRS can assess the tax immediately. Your only remaining route to challenge the bill is to pay it in full and then sue for a refund in district court or the Court of Federal Claims. The petition goes to the court, not to the IRS, and courts enforce the 90-day rule strictly. One day late forfeits pre-payment judicial review.
Paying After an Assessment
Once the IRS formally assesses additional tax, whether because you agreed with the findings or because the appeal and court deadlines passed, it sends a Notice and Demand for Payment. You have 21 calendar days from that notice to pay. If the amount is $100,000 or more, the window shrinks to 10 business days.11Office of the Law Revision Counsel. 26 U.S.C. 6651 – Failure to File Tax Return or to Pay Tax
Miss that deadline and a failure-to-pay penalty of 0.5 percent of the unpaid balance kicks in for each month or partial month the tax remains unpaid, up to 25 percent.11Office of the Law Revision Counsel. 26 U.S.C. 6651 – Failure to File Tax Return or to Pay Tax Interest runs on top of that, and it runs from the original due date of the return, not from the date of the notice. Rates are set quarterly.12Office of the Law Revision Counsel. 26 U.S. Code 6621 – Determination of Rate of Interest Because interest compounds daily from the original filing deadline, a long audit can produce a surprisingly large interest charge even on a modest deficiency.
Accuracy-related penalties can also apply: 20 percent of the underpayment for negligence, disregard of the rules, or a substantial understatement of income tax, and 75 percent of the fraudulent portion if the IRS proves fraud by clear and convincing evidence.13Office of the Law Revision Counsel. 26 U.S.C. 6662 – Imposition of Accuracy-Related Penalty on Underpayments14Office of the Law Revision Counsel. 26 U.S.C. 6663 – Imposition of Fraud Penalty
If you can’t pay in full, an installment agreement is usually the fastest way to stop the deadline from becoming a bigger problem. Individuals who owe $50,000 or less in combined tax, penalties, and interest can set up a simple payment plan, often online, with up to 10 years to pay.15Internal Revenue Service. Simple Payment Plans for Individuals and Businesses Short-term plans give you up to 180 days to pay in full with no setup fee.16Internal Revenue Service. Payment Plans; Installment Agreements Interest keeps accruing, but a plan cuts the failure-to-pay penalty rate.
How Long the IRS Has to Collect
Once an assessment is made, the IRS has 10 years to collect through levies, liens, or court proceedings.17Office of the Law Revision Counsel. 26 U.S.C. 6502 – Collection After Assessment This is separate from the three-year assessment window. The assessment deadline governs when the IRS can audit; the collection deadline governs how long it can pursue payment afterward.
Certain events pause the 10-year clock, including bankruptcy, an offer in compromise, and an installment agreement, which can extend the collection period by the duration of the agreement. When the 10 years run out, the IRS can no longer legally collect.
Missed a Deadline? Audit Reconsideration
If you missed your chance during the original audit, whether because you moved and never got the letters or simply didn’t have the documentation at the time, audit reconsideration is a second window. You can request it as long as the assessed tax remains unpaid.18Internal Revenue Service. Audit Reconsideration Process for Correspondence Examination Audits by Mail
Review your examination report (Form 4549), identify the specific items you disagree with, and gather documentation you didn’t provide before. Submit through the IRS Document Upload Tool or by mail to the office that handled your audit. If you’ve already paid the assessed amount, reconsideration is not available; you’d need to file an amended return instead.
How Long to Keep Records So the Deadlines Don’t Catch You Empty-Handed
Match your record retention to the longest statute of limitations that could apply to you. At minimum, keep supporting documentation for at least three years after filing. If there’s any chance you underreported income by more than 25 percent, keep records for six years. For employment taxes, keep records for at least four years after filing the fourth-quarter return for the year.19Internal Revenue Service. Employment Tax Recordkeeping
Records tied to assets you still own, such as investment property, rental real estate, and retirement accounts, should be kept as long as you hold the asset plus at least three years after the sale or final distribution is reported. Records for carryover deductions like charitable contributions or net operating losses should be kept until those carryovers no longer affect any tax year. Seven years covers almost every scenario short of fraud, where no time limit applies at all.