Taxpayers often ask, “How long do I have to respond in an IRS audit?” The correct answer starts with one practical rule: the IRS sets your next due date on the letter or notice in front of you, and you must treat that due date as real even when you plan to contest the audit. The IRS confirms that it shows “the date when the next response is due” in certain online audit-status views, but your letter controls the next step.
You should also understand the stakes of missing a deadline. If you do not respond by the date shown on the IRS letter or notice, the IRS can complete the audit based on what it has and then issue an audit report with proposed changes. When you face a high-risk audit, including an eggshell audit or reverse eggshell audit, rushed and unstructured responses can create criminal tax exposure. In those cases, you still respond promptly, but you do it strategically, under counsel, and with a plan to control the facts you present and the statements you make.
Typical Early-Stage Response Windows and How the IRS Handles Extension Requests
Early in an examination, the IRS usually requests documents, explanations, and substantiation by a specific due date stated in writing. The IRS initiates audits by mail, not by telephone, and the letter provides instructions and contact information. If you need more time, ask before the due date and follow the method the IRS describes for your audit type.
For audits conducted by mail, the IRS instructs taxpayers to fax or mail a written extension request to the number or address shown on the letter, and the IRS states that it can “ordinarily grant” a one-time automatic 30-day extension for that type of audit. For audits conducted through an in-person interview, you should contact the assigned auditor to request additional time, and you can escalate to the auditor’s manager if needed.
You should also build proof of delivery into your process. The IRS advises taxpayers to use delivery confirmation, and it describes an online status option for certain correspondence-audit phone numbers. In correspondence exams, IRS Publication 3498-A explains that the IRS will send an acknowledgment letter within 30 days after it receives documents submitted by mail or fax, which gives you another way to track whether the IRS received what you sent.
Finally, you should understand how quickly an information request can harden into enforcement in larger or more complex exams. In some IRS programs, the IRS uses a structured Information Document Request (IDR) enforcement process, and the pre-summons letter can require a response within 10 business days before the IRS pursues a summons.. You should not assume that every audit uses this IDR enforcement track, but you should assume that missed due dates invite escalation.
The Deadlines That Matter Most: 30-Day Letters, Appeals Windows, and the Path to a 90-Day Notice
Many audits resolve through a back-and-forth information exchange, but response timing becomes most critical when the IRS reaches proposed adjustments. At that stage, the IRS commonly issues a “30-day letter” package (often associated with Letter 525 or similar correspondence) that outlines proposed changes and explains how to agree or request Appeals consideration. The IRS states that Letter 525 serves as a “General 30-Day Letter” and that it outlines options, including submitting an Appeals request if you disagree.
You generally have 30 days from the date of the 30-day letter to tell the IRS whether you accept the proposed changes or appeal them, and IRS Publication 556 states that general rule. The Taxpayer Advocate Service similarly describes Letter 525 as giving 30 days to request Appeals when you disagree with proposed changes. ou should still read the specific letter carefully because the IRS sets the response period in the letter you received.
If you miss the 30-day response window and you do not reach a resolution, the IRS can move the case into the statutory deficiency route by issuing a Notice of Deficiency, often called a “90-day letter.” IRS Publication 3498 explains this sequence directly: if you do not respond to the 30-day letter or settle through Appeals, the IRS will send a 90-day letter. The Klasing firm’s resources describe the same turning point and emphasize that the 30-day letter functions as your gateway to Appeals, while the 90-day letter functions as the statutory notice of deficiency. If you do not file a tax court petition before the 90-day period ends, the IRS will immediately asses and begin collection action.
The Non-Extendable Deadline You Cannot Miss: The Notice of Deficiency and U.S. Tax Court Filing Time
Certain IRS response times allow some flexibility. The most important deadline does not. If the IRS issues a Notice of Deficiency, federal law generally gives you 90 days to file a petition in the U.S. Tax Court, or 150 days if the notice is addressed to a person outside the United States. IRS Publication 3498 states the same 90-day (or 150-day) timeframe. IRS Publication 3498-A adds a critical point: the law sets the time to petition, and the IRS cannot change it. The IRS repeats the same practical warning in its audit guidance: it cannot grant additional time to submit supporting documentation once you receive a Notice of Deficiency by certified mail, and it cannot extend the time to petition the U.S. Tax Court beyond the original 90 days.
California timing can matter in parallel. If the IRS makes a final federal determination that adjusts items on your federal return, California generally requires you to notify the Franchise Tax Board within six months of that final federal determination. After a California audit, the FTB typically issues a Notice of Proposed Assessment (NPA), and the FTB states that you have 60 days to protest if you disagree.
How to Manage Response Deadlines Without Creating Criminal Tax Exposure
Deadlines matter, but how you respond matters just as much, especially in high-risk audits that carry criminal tax exposure. The most dangerous pattern we see involves taxpayers who scramble to meet a deadline by submitting disorganized documents, guessing at facts, or volunteering narratives to “explain” discrepancies. Those decisions can create inadvertent criminal tax admissions, lock in an inconsistent story, or provide the roadmap that a Fraud Referral Specialist or the IRS Criminal Investigation Division needs to develop a criminal tax case. Reverse eggshell audits, in particular, can run as parallel civil and criminal tracks while the IRS disguises the criminal tax investigation inside a civil posture.
You should still respond on time, but you should do it with disciplined damage control. That usually means you (1) identify the exact letter type and due date, (2) request a written extension early when you need it, (3) control communications through counsel, and (4) avoid taxpayer interviews when the facts suggest potential criminal tax exposure. The IRS recognizes that you have a right to representation during an audit. In the right case, counsel can also help you consider the appropriate and lawful use of constitutional protections, including the Fifth Amendment, without triggering additional problems through an overbroad or careless assertion.
Contact the Tax Law Offices of David W. Klasing if You Are Worried About an IRS Tax Audit
If you worry about a high-risk IRS tax audit, you should act early and you should choose a team that can handle both the civil audit chess match and the criminal tax exposure that can hide inside it. At the Tax Law Offices of David W. Klasing, we focus on civil and criminal federal tax controversies, and we staff matters with dual-licensed tax professionals who approach audits with damage control in mind, not box checking. When the facts present eggshell or reverse eggshell risk, we help clients control communications, develop substantiation under privilege, and reduce the chance that a routine exam escalates into a CID problem. As our firm publicly reports, we have never had an audit client that we represented criminally prosecuted for tax crimes in the history of the firm, even where the audit facts created real criminal tax exposure.
You also gain a practical advantage when you hire a firm that integrates legal strategy with tax-technical execution under one roof. David W. Klasing holds active California attorney licensure and a California CPA license, and he also earned an M.S.-Tax degree (Master of Science in Taxation).
You should start with a focused, reduced-rate initial consultation that lets us identify the real deadlines, the real risks, and the fastest path to control. You should not wait until the IRS hardens its position or starts asking questions that can later read like criminal tax admissions. Call us at (800) 681-1295 or schedule online HERE, and we will start with a privileged risk assessment and a plan designed to protect your liberty and your net worth.
