Short answer
A notice of deficiency, often called a 90-day letter, is the IRS’s legal notice that it proposes more tax. You have 90 days from its mailing date (150 days if addressed outside the US) to petition the U.S. Tax Court without paying first. The IRS cannot extend that deadline; if you miss it, the tax is assessed and billed.
Key takeaways
- A notice of deficiency (Letter 3219 after a mail audit, Letter 531 after an in-person audit, CP3219A after an income-matching review) is a proposal, not a bill.
- You have 90 days from the notice’s mailing date, or 150 days if it is addressed to you outside the United States, to petition the Tax Court; a petition filed by the last date printed on the notice counts as on time.
- Neither the IRS nor the Tax Court can extend that period, and writing to the IRS or calling the Taxpayer Advocate does not pause it.
- The Tax Court is generally the only court where you can dispute the tax before paying it; filing costs $60, and the fee can be waived.
- If you miss the deadline, the IRS assesses the tax and bills you; what remains is audit reconsideration, or paying and suing for a refund.
What a notice of deficiency is
When the IRS decides you owe more income, estate, gift or certain excise tax, IRC 6212 authorizes it to send a notice of deficiency by certified or registered mail. A notice mailed to your last known address is legally sufficient even if you never see it, which is why keeping your address current with the IRS matters. Publication 1035 puts it plainly: “The notice is not an assessment of tax. It is a proposed deficiency.” It is the document that gives you the right to go to the U.S. Tax Court.
You may know it by its letter number:
| Notice | Usually follows | Read more |
|---|---|---|
| Letter 3219, Notice of Deficiency | An audit by mail where you didn’t respond to the 30-day letter or didn’t settle | The 30-day letter |
| Letter 531, Notice of Deficiency | An in-person (office or field) audit | Types of IRS audits |
| CP3219A, Statutory Notice of Deficiency | A change based on information from employers, banks and others, often after an unanswered CP2000, which is not an audit | CP3219A explained |
Every version shows the proposed changes, the extra tax and any penalties, and a last day to petition the Tax Court. Most arrive after a 30-day letter went unanswered or an Appeals review ended without agreement. Publication 1035 adds that the IRS may also issue one when you decline to extend the assessment statute.
The 90-day deadline: how it is counted and why it is strict
How the period works under IRC 6213(a) and the Tax Court’s guidance:
- 90 or 150 days. The petition is due within 90 days after the notice is mailed, or 150 days if it is addressed to a person outside the United States.
- The printed date protects you. A petition filed on or before the last date the IRS specifies in the notice “shall be treated as timely filed,” so use that date. If you can’t find one, count from the mailing date, which is usually stamped on the notice.
- Weekends and holidays. If the last day falls on a Saturday, Sunday or District of Columbia legal holiday, the next business day still counts.
- E-filing cutoff. The Tax Court must receive an electronically filed petition by 11:59 pm Eastern Time on the last day.
- Mailing. Under IRC 7502, a properly addressed, postage-paid document postmarked on or before the deadline is generally treated as filed on time, and certified or registered mail gives you proof. Don’t wait for the last day to test it.
- Talking doesn’t pause it. Sending the IRS documents or contacting the Taxpayer Advocate Service does not extend the time to petition, according to the Taxpayer Advocate Service.
Publication 1035 notes one narrow exception: the IRS and the taxpayer can agree to rescind a notice of deficiency in certain circumstances. Don’t plan around it; it requires the IRS’s agreement.
What the IRS can and cannot do during the 90 days
The notice protects you as well as starting a clock. Under IRC 6213(a), the IRS generally cannot assess the proposed tax, levy, or sue to collect it until the 90 or 150 days have passed. If you petition in time, that bar lasts until the Tax Court’s decision is final.
- No bill yet. You should not get a balance-due notice for the proposed amount during the period. The exceptions are rare jeopardy and termination assessments.
- The IRS’s own clock pauses. Under IRC 6503(a), mailing the notice suspends the IRS’s time to assess while it is barred from assessing, plus 60 days.
- No second notice after you petition. Once you file a timely petition, IRC 6212(c) generally stops the IRS from sending another notice of deficiency for the same year, with exceptions such as fraud.
- Interest keeps running. If the tax is upheld, interest is charged from the return’s due date at the federal short-term rate plus 3 percentage points, reset quarterly (7% (IRS.gov, Jul-Dec 2026) this quarter). Publication 3498 says an advance payment or an IRC 6603 deposit stops interest on the amount paid. See how IRS interest works.
Your options once the notice arrives
| Option | How | Deadline | What happens next |
|---|---|---|---|
| Agree | Sign and return the waiver that came with the notice (Form 5564, Notice of Deficiency-Waiver, for Letter 3219 and CP3219A) | Within the 90 days | The IRS assesses the tax and sends a bill; pay or set up a plan |
| Send the IRS documents | Reply to the IRS with an explanation and documents, as CP3219A invites | Within the 90 days | The IRS may resolve it, but this does not extend the petition deadline |
| Petition the Tax Court | File a petition with the Tax Court (not the IRS) and pay the $60 (IRS.gov, 2026) fee or ask for a waiver | By the last date on the notice | The IRS files an Answer; you will normally get a chance to settle with Appeals before trial |
| Pay, then sue for a refund | Pay the tax in full, file a refund claim with the IRS, then sue in U.S. District Court or the Court of Federal Claims | Refund claim and suit deadlines apply | A court reviews the case after payment |
| Do nothing | No response | n/a | The tax is assessed with penalties and interest and you receive a bill |
Publication 5 calls the Tax Court “generally a ‘prepayment’ forum,” while the district courts and the Court of Federal Claims generally hear tax cases “only after you have fully paid the amount and timely filed a claim for refund.” For most people, the petition is the practical way to get an independent review without paying first. If you aren’t sure the IRS is wrong, our guide on whether to agree or fight helps you weigh it, and disputing an IRS balance compares every route.
How to petition the Tax Court, step by step
- Find the last day to petition. Look for the last day to petition printed on the notice and count from its mailing date: 90 days, or 150 if it was addressed to you outside the United States. Write the date down and work back from it.
- Decide whether to agree or dispute. If you accept the changes, sign and return the waiver form that came with the notice (Form 5564 for many letters). If you disagree with any part, plan to petition the Tax Court, not the IRS.
- Prepare the petition. Use the Tax Court’s DAWSON petition generator, or fill in the simplified petition, T.C. Form 2, on paper. List each IRS adjustment you dispute and the facts behind your position, and include a copy of the notice of deficiency.
- Choose small case or regular procedure. If the amount in dispute for each year, including penalties, is within the small tax case limit, you may elect the informal small case procedure. Small case decisions cannot be appealed.
- Pay the filing fee or ask for a waiver. The Tax Court’s filing fee is $60. If you cannot pay, file the court’s Application for Waiver of Filing Fee, signed under penalty of perjury.
- File with the Tax Court on time and keep proof. E-filed petitions must reach the court by 11:59 pm Eastern Time on the last day. If you mail it, use certified or registered mail and keep the receipt. Then watch for the IRS Answer and contact from IRS Appeals or IRS Counsel about settlement.
The Tax Court’s Getting Started page for petitioners has the petition form, the fee-waiver application and DAWSON instructions. You may represent yourself (Publication 5 calls this appearing “pro se”) or use a representative admitted to practice before the Tax Court.
The small tax case option
If the deficiency in dispute, including additions to tax and penalties, is $50,000 (IRS.gov, 2026) or less for any one year, you may ask for the small tax case (S case) procedure (IRC 7463; Tax Court case procedure page). It is more informal, and the court generally agrees if you qualify. The trade-off: the decision “shall not be reviewed in any other court and shall not be treated as a precedent.” You can ask to switch to small case procedure any time before trial begins.
| Rule | Small tax case | Regular case | Source |
|---|---|---|---|
| Amount in dispute | $50,000 or less per year, including penalties | Any amount | IRC 7463(a) |
| Appeal of the decision | Not allowed | To a federal court of appeals | IRC 7463(b); Tax Court |
| Precedent | None | Yes | IRC 7463(b) |
| Filing fee | $60, waivable | $60, waivable | ustaxcourt.gov |
See Tax Court small case procedure for when it fits.
After you petition: settlement with Appeals
Filing a petition doesn’t mean you will stand in front of a judge. The Tax Court says the IRS next files an Answer, which names the IRS attorney handling the case. Publication 5 says that if you did not already appeal within the IRS, “you will normally have an opportunity to attempt settlement with Appeals while you are waiting for your trial,” and you may not need to go to trial if you settle first. Publication 1035 says you “will generally have the opportunity for a pretrial settlement.” If you don’t settle, the case is tried, either by you or by a representative admitted to the Tax Court.
Publication 5 warns that the Tax Court can impose a penalty if it finds a case was filed primarily for delay or on a frivolous position, so petition only on real disagreements over facts or law.
If you missed the 90 days
The Taxpayer Advocate Service says that after the deadline “you won’t be able to have a judge review your case without first paying the amount due,” and the tax is assessed with penalties and interest. A bill such as a CP14 follows, then the normal collection notices. You still have routes:
- Audit reconsideration if the tax is unpaid and you have new information the IRS hasn’t seen. See audit reconsideration.
- Pay and claim a refund. Pay in full, file a refund claim, and if it is denied, sue in district court or the Court of Federal Claims; Publication 5 says you have 2 years from the notice of claim disallowance to sue.
- Not a liability challenge at a CDP hearing. Under IRC 6330(c)(2)(B), a Collection Due Process hearing can consider the amount of tax only if you did not receive a notice of deficiency for it and had no other chance to dispute it.
- If the tax is right but unaffordable, compare your Fresh Start options.
Our page on missed audit deadlines goes through each route in order.
Doing it yourself, free help, and when a representative is worth it
The Tax Court is built to be usable without a lawyer: a fill-in petition, online filing, and small case procedures for smaller disputes. Doing it yourself is reasonable when the issue is narrow and well documented. Help is worth more when the amount is large, several years or business income are involved, penalties such as fraud are proposed, or you aren’t sure whether a petition or a refund suit fits better.
- Low Income Taxpayer Clinics: LITCs can represent eligible taxpayers “before the IRS or in court” on audits, appeals and other tax disputes, for free or a small fee.
- Taxpayer Advocate Service: 877-777-4778 (IRS.gov, 2026); helpful when an IRS problem causes hardship, but contacting TAS does not extend your petition deadline.
- A representative: an attorney, CPA or enrolled agent can deal with the IRS for you under a Form 2848; to appear for you in the Tax Court itself, the person must be admitted to practice there.
Global Gate Tax Relief offers a free consultation, reviews your notice and IRS transcripts, and tells you plainly if you can handle it yourself. If it takes the case, it quotes a flat fee upfront and does not promise a result. With a petition deadline running, request a free review now or call 1-877-800-8180.
Frequently asked questions
It is a notice of deficiency: the IRS’s legal notice that it proposes more tax. It gives you 90 days from its mailing date (150 days if addressed outside the US) to petition the U.S. Tax Court before the tax is assessed.
No. The Tax Court says it cannot extend the time to petition, and the IRS says it cannot either. Sending the IRS documents or contacting the Taxpayer Advocate Service does not pause the deadline.
No. Letter 3219 is a notice of deficiency, usually after an audit by mail. It proposes tax; the IRS can’t assess it until the petition period ends. If you don’t agree and don’t petition, the tax is assessed and you then receive a bill.
The filing fee is $60. The Tax Court may waive it if you show you cannot pay, using its Application for Waiver of Filing Fee signed under penalty of perjury.
No. The petition goes to the U.S. Tax Court, electronically through DAWSON or on paper by mail or in person. You can also write to the IRS, but that does not replace or extend the petition.
Usually, yes. Publication 5 says that if you did not appeal within the IRS earlier, you will normally have a chance to settle with IRS Appeals while you wait for trial, and you may not need to go to trial if you settle.
The tax is assessed and billed, and you can’t get Tax Court review without paying first. Options are audit reconsideration if the tax is unpaid and you have new information, or paying in full, claiming a refund and suing in district court or the Court of Federal Claims.
Sources
- 26 U.S.C. 6212, Notice of deficiency
- 26 U.S.C. 6213, Restrictions applicable to deficiencies; petition to Tax Court
- 26 U.S.C. 6503, Suspension of running of period of limitation
- 26 U.S.C. 7463, Disputes involving $50,000 or less
- 26 U.S.C. 7502, Timely mailing treated as timely filing and paying
- 26 U.S.C. 6330, Notice and opportunity for hearing before levy
- U.S. Tax Court: Getting started for petitioners
- U.S. Tax Court: Case procedure information
- IRS Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021)
- IRS Publication 1035, Extending the Tax Assessment Period (Rev. 9-2017)
- IRS Publication 3498, The Examination Process (Rev. 5-2025)
- IRS: Understanding your CP3219A notice (reviewed 2 Oct 2026)
- Taxpayer Advocate Service: Letter 3219 (updated 14 Apr 2026)
- IRS: Letters and notices offering an appeal opportunity (reviewed 16 Jul 2026)
- IRS: Understanding your CP14 notice
- IRS: Quarterly interest rates
- IRS: Low Income Taxpayer Clinics
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