What a Notice of Deficiency Is
A notice of deficiency is the IRS's proposed assessment. The agency has decided you owe more tax than you reported, usually after an examination or after a proposal you did not answer, and the notice states the amount and tells you it intends to put that amount on your account. Federal law bars the IRS from assessing the deficiency, and from levying to collect it, until the notice has been mailed and the period printed on it has run. The period is 90 days, or 150 days when the notice is addressed to a person outside the United States.
The reason the notice matters more than any other letter in the sequence is what it opens. A petition filed in the United States Tax Court within that period is the only way to contest the amount before paying it. Every other route to a judge requires paying first. Lawyers call it the 90-day letter for that reason, and the date printed on it is worth more than everything else in the envelope.
The notice arrives by certified or registered mail, and mailing it to your last known address is enough. The statute is explicit on that point, and a notice that went to a house you moved out of two years ago still counts as mailed. Actual receipt is not required for the period to run.
How the Notice Differs From a CP2000 and From the Collection Notices
Two other notices get confused with this one, from opposite directions.
A CP2000 comes earlier. The IRS matched what a payer reported against what you filed, found a difference, and proposed a change. Answering it is a correspondence exchange with the IRS, and no court deadline runs on it. When that exchange does not close the difference, the notice of deficiency is the step that follows, and the court deadline begins there. A CP2000 is a proposal you can talk about. A notice of deficiency is a proposal with a courtroom attached and a clock running.
The CP504 comes later, and it belongs to a different stage entirely. Once a deficiency is assessed, the IRS sends a first bill, then reminders, then a CP504 headed Notice of Intent to Levy, and then a Final Notice that carries the right to a collection due process hearing. The collection notices are about collecting a tax that is already on the books. Our CP504 guide explains why that notice reaches only a state tax refund and starts no hearing clock, and the collection due process page walks the whole sequence. The notice of deficiency sits before all of them, at the last moment the amount itself is open, which is why the choice you make now decides what the later notices can do.
How the 90 Days Are Counted
The period runs from the date the notice was mailed. The day the envelope reached you does not enter the count, and a notice that chased an old address or sat at a foreign post office has spent part of its period before anyone opened it.
Two rules soften the arithmetic, and both come from the statute itself. First, if the last day falls on a Saturday, a Sunday, or a legal holiday in the District of Columbia, that day is not counted as the last day. Second, since 1998 the notice has had to print the last date for filing a petition, and a petition filed on or before the printed date is treated as timely even where the IRS computed it generously. So the date on the face of the notice is the operative date. Calendar that one, and do not recount it in your own favor.
The 150-day period applies when the notice is addressed to a person outside the United States, which matters for Americans abroad, including our clients in Israel. The address the IRS used is the first thing to check. Federal tax law also treats a timely mailed document as timely filed, so the postmark and the proof of mailing are what to keep.
One more line from the IRS's own page on this notice deserves its own paragraph. The agency says it will work with you to resolve the issues during the 90 days, and that doing so does not extend the time to file a petition in Tax Court. Negotiating and filing are separate tracks, and the second one is the one with the date on it.
Holding a CP3219A and not sure what day it is?
The mailing date, the printed last day and the address block decide everything else, and reading them takes fifteen minutes. A free 30-minute consult does that first, then maps the three choices against your numbers.
Book your free consultThe Three Choices the Notice Gives You
The notice gives you three choices, and silence is one of them.
Petition the Tax Court. A petition filed within the period keeps the amount unassessed until the Tax Court's decision is final, and it is the only prepayment forum you will get. The ten-year collection period is paused while the IRS is barred from assessing, and for 60 days after. The Tax Court posts its filing fee on its website. Filing the petition does not commit you to a trial. What it does is hold the amount open while the dispute is worked, with a judge available if the two sides cannot agree.
Agree, and pay or arrange payment. The notice refers to Form 5564, the Notice of Deficiency Waiver, which is the form for agreeing. Signing it is how you accept the amount, and once the amount is accepted the only question left is how to pay. An installment agreement or an offer in compromise is worked out on the collection side, and our offer in compromise calculator shows the figure the IRS actually looks at when it weighs an offer.
Do nothing. When the period runs with no petition and no waiver, the IRS assesses the deficiency. The first bill follows, then the reminders, then the CP504, and then the Final Notice that starts the collection due process clock. Doing nothing is a choice with a schedule attached, and the schedule is the collection ladder.
Why the 90 Days Are Absolute in Florida
People ask whether a late petition can be heard, and the honest answer depends on where you live.
In 2022 the Supreme Court held in Boechler that the 30-day deadline for petitioning the Tax Court from a collection due process determination is an ordinary deadline rather than a jurisdictional one, so a court can extend it by equitable tolling where something extraordinary prevented a timely filing. The Boechler ruling was about the collection deadline only. Since then three federal courts of appeals, the Third Circuit in 2023, the Second Circuit in 2025 and the Sixth Circuit in August 2025, have extended the same reasoning to the 90-day deficiency deadline. Two others, the Seventh and the Ninth, treated the deadline as jurisdictional before Boechler and have not revisited the question. The Tax Court itself, in decisions from 2022 and 2023, continues to treat the 90 days as jurisdictional outside the circuits that have ruled otherwise, which means it holds it has no power to hear a petition filed after the period.
Florida sits in the Eleventh Circuit, and the Eleventh Circuit has not decided the question. So for a Florida taxpayer the working rule is the Tax Court's default, and the Tax Court's default is dismissal. Nobody can promise you that a court will toll this deadline for a Florida petition, and this office does not. Treat the 90 days as absolute, and file inside them.
What Happens After the 90 Days Pass
The deficiency is assessed, and the collection side begins. Within 60 days of the assessment the IRS sends its notice and demand, which arrives as a CP14, and the amount on it is due by the date shown, generally 21 days later (10 business days when the amount is $100,000 or more). The reminders and the CP504 follow over the following months, and then the Final Notice with its own 30-day clock, which is the subject of our collection due process guide.
The 90-day letter is the only notice on the ladder where the deadline buys you Tax Court, and everything after it is collection rather than liability. Once the assessment is made, the sequence runs through CP504, then the final notice of intent to levy which carries the Collection Due Process right, and the notice of federal tax lien can be filed alongside any of it.
Three routes survive assessment, and none of them is as good as the one you had. First, you can pay the tax in full and sue for a refund, and the courts require full payment before that suit can be brought. Second, you can ask the IRS for an audit reconsideration, which is an administrative request rather than a right. Third, there is one later chance to dispute the amount itself, and it comes at the collection due process hearing. The law allows a liability challenge there only if you did not receive a notice of deficiency and did not otherwise have an opportunity to dispute the tax. A taxpayer who received the 90-day letter and let it run has spent the chance. A taxpayer who genuinely never received it, because it went to a last known address they had left, may still have it, and that posture comes up often with expatriates and recent movers.
One caution attaches to that third route, from the Supreme Court's 2025 decision in Zuch. The Tax Court loses its power over a collection due process case once the IRS stops pursuing the levy, so the hearing is a dependable way to stop a levy and an undependable way to litigate how much you owe. Where the amount is the fight, the petition inside the 90 days was the forum built for it, which is the whole argument for filing on time.
How We Work a Notice of Deficiency
The first step is fast and it is the same every time. We read the notice, confirm the mailing date and the printed last day, and check the address the IRS used, because the address decides whether the period is 90 days or 150. Then we pull the account transcripts, so the numbers on the notice can be compared with what the IRS actually has.
From there the choice is made with the numbers in front of you. Where the amount is wrong, the petition goes in before the printed date, and this firm is admitted to the United States Tax Court, so the litigation is work we do rather than send elsewhere. A Tax Court petition is litigation and is quoted per matter after we read the notice. The consult is free and takes 30 minutes. Where the amount is right and the problem is paying it, the waiver and the collection alternative are the better use of the money, and the offer in compromise calculator gives a first read on what the IRS would accept.
Where the balance traces back to an international reporting penalty rather than to income tax, the notice in your hand is probably a different one. Our CP15 guide covers the penalty notices that never carry deficiency procedures at all, and where a payroll tax balance is being collected from an owner personally, the trust fund recovery penalty guide covers that route and its own deadlines.
Frequently Asked Questions
What Is an IRS Notice of Deficiency?
A notice of deficiency is the IRS's formal statement that it intends to assess more tax than you reported, with the amount printed on it. Federal law bars the IRS from assessing that amount, or levying to collect it, until the notice has been mailed and the period on it has run, which is 90 days, or 150 days when the notice is addressed to a person outside the United States. The notice matters because a petition filed in the United States Tax Court inside that period is the only way to contest the amount before paying it. The IRS mails it as a CP3219A, and lawyers call it the 90-day letter.
What Happens If I Ignore a Notice of Deficiency?
The IRS assesses the deficiency when the period ends, and the collection sequence starts. A first bill arrives within 60 days of the assessment, due by the date shown on it, and the reminders, the CP504 and the Final Notice follow over the following months. The chance to contest the amount before paying is gone. What survives is paying in full and suing for a refund, asking the IRS for an audit reconsideration, or raising the amount at a collection due process hearing, and that last route is open only to a taxpayer who never received the deficiency notice and never had another chance to dispute it. Ignoring the notice is a choice, and it is the most expensive of the three.
Can I Get More Time on a 90-Day Letter?
No. The period is fixed by statute and the IRS cannot extend it. The IRS's own page on this notice says the agency will work with you during the 90 days and that doing so does not extend the time to file a petition. The only cushions are the ones built into the law. A last day that falls on a Saturday, a Sunday or a legal holiday in the District of Columbia is not counted, and a petition filed by the last date printed on the notice is timely. Whether a court can forgive a late petition is unsettled. Three federal appeals courts have said yes, two have said no, and the court that covers Florida has not ruled. In Florida, plan on the deadline being absolute.
Is CP3219A the Same as an Audit?
No. An audit, or the mismatch proposal that arrives as a CP2000, is the step before. The examiner or the computer proposed a change and asked you to agree or explain. The CP3219A is what follows when that step did not resolve the difference, and it is the formal proposed assessment, the first notice in the sequence that carries a court deadline. A notice that went to an old address still counts as mailed, so some people meet the CP3219A without having seen the earlier letter, and the 90 days run just the same.
Does the 90 Days Start When the Notice Was Mailed or When I Received It?
When it was mailed. The statute counts the period from the mailing of the notice, and mailing to your last known address is enough even if you never received it. A notice that went to a house you left, or that sat in a foreign post office for three weeks, has already spent part of its period. Since 1998 the notice has had to print the last day for filing, and a petition filed by that printed date is treated as timely, so the printed date is the one to calendar. The 150-day period applies when the notice is addressed to a person outside the United States.
Do You Handle Tax Court Petitions, and What Does It Cost?
Yes. The firm is admitted to the United States Tax Court, and the petition and the case behind it are courtroom work we do rather than refer away. A Tax Court petition is litigation and is quoted per matter after we read the notice. The consult is free and takes 30 minutes. The Tax Court posts its own filing fee on its website. Where the amount is right and the problem is paying it, the waiver and the collection alternative are handled here on a flat fee quoted once we have read the notice and pulled your transcripts, and most of the work runs by phone and video.
Common Situations
The notice that went to the old address. A man moved from Orlando to Tel Aviv and never updated the address the IRS had on file. The notice of deficiency went to the Orlando apartment. Under the last known address rule it was valid when mailed, the 90 days ran with no petition, and the deficiency was assessed. Two years later a Final Notice reached him abroad. Because he had never received the deficiency notice and had never had another chance to dispute the amount, the question at the collection due process hearing was the amount itself, rather than only how it would be collected.
The negotiation that ate the deadline. A restaurant owner received a CP3219A proposing a $48,000 deficiency, called the number on the notice, and spent ten weeks sending documents to the examiner who had proposed the change. The examiner was responsive and the number was coming down. Day 90 passed during the exchange with no petition on file, and the remaining amount was assessed. The IRS's own page on this notice says that working with the agency during the period does not extend the time to petition, and the two tracks have to run at the same time.
Sources of Law
- Authority for the notice. 26 U.S.C. §6212(a) (sent by certified or registered mail) and §6212(b) (mailing to the last known address is sufficient, even where the taxpayer is deceased or under a legal disability; actual receipt is not required).
- The deadline. 26 U.S.C. §6213(a) (a petition within 90 days, or 150 days if the notice is addressed to a person outside the United States, after the notice is mailed, not counting a Saturday, Sunday or legal holiday in the District of Columbia as the last day; a petition filed on or before the last date the IRS specifies in the notice is treated as timely; no assessment and no levy until the period expires and, where a petition is filed, until the Tax Court decision is final). The requirement that the notice state the last day dates from the 1998 amendment, Pub. L. 105-206 §3463. Form 5564, Notice of Deficiency Waiver, is the form for agreeing; the irs.gov CP3219A page states that working with the IRS during the period does not extend the time to petition.
- Timely mailing. 26 U.S.C. §7502 (timely mailing treated as timely filing) and §7503 (a due date falling on a Saturday, Sunday or legal holiday rolls to the next business day), which IRM 8.22.5.3.1 applies to collection hearing requests.
- After assessment. 26 U.S.C. §6303(a) (notice and demand within 60 days after assessment) and §6651(a)(3) (21 calendar days, or 10 business days at $100,000 or more). Suspension of the ten-year collection period while assessment is barred and for 60 days after, §6503(a); the ten years themselves, §6502(a)(1). Full payment before a refund suit (Flora).
- The later chance at a collection hearing. 26 U.S.C. §6330(c)(2)(B) (the underlying liability may be raised only if the person did not receive a statutory notice of deficiency and did not otherwise have an opportunity to dispute it); IRM 8.22.8 (what counts as a prior opportunity); Form 12153 (Rev. 7-2022), p. 3.
- The jurisdictional split. Boechler, P.C. v. Commissioner, 596 U.S. 199, 142 S. Ct. 1493 (2022) (the §6330(d)(1) deadline is nonjurisdictional and subject to equitable tolling; the opinion does not reach §6213(a)). Holding §6213(a) nonjurisdictional, Culp v. Commissioner, 75 F.4th 196 (3d Cir. 2023), cert. denied June 24, 2024; Buller v. Commissioner (2d Cir. 2025); Oquendo v. Commissioner, No. 24-1205 (6th Cir. Aug. 25, 2025). Holding it jurisdictional before Boechler and not since revisited, the Seventh Circuit (Tilden) and the Ninth Circuit (Organic Cannabis Foundation). The Tax Court's default, Hallmark Research Collective v. Commissioner, 159 T.C. 126 (2022), reaffirmed in Sanders v. Commissioner, 161 T.C. 112 (2023). The Eleventh Circuit, which covers Florida, has not ruled. Pub. 594 (Rev. 1-2026) describes the diligence and extraordinary-circumstances showing for a late collection petition only.
- Commissioner v. Zuch, No. 24-416 (U.S. June 12, 2025) (the Tax Court loses jurisdiction over a collection due process case once the IRS no longer pursues the levy). (sources verified against the primary texts August 28, 2026; retrieved for this page September 16, 2026)
The Letter That Sat in a Drawer
The calls I take about this notice almost always start the same way. The envelope arrived, it looked like the two or three IRS letters before it, and it sat in a drawer for 60 days while the family waited for the accountant to call back. By the time someone reads the words Tax Court on the first page, a third of the period is left and nobody has the return in front of them.
In 14 years of law practice, I litigate tax, business and estate disputes, and a notice read too late is where many collection cases start.
I have a few take-home points.
The first is the date on the letter. The period runs from mailing rather than from receipt, and the notice prints the last day (it has had to since 1998). I calendar that printed day before I read anything else in the envelope, because every other question on this page can wait a week and that one cannot.
The second is the address block. The longer 150-day period belongs to a notice addressed to a person outside the United States, so the address the IRS used is the fact that fixes the deadline, and it takes ten seconds to check.
The third is the negotiation. The IRS will keep talking to you during the period, and its own page says the talking does not extend the time to file. I treat the examiner's phone call and the petition as two separate tracks, and the petition track is the one with the date on it.
Avoid waiting for the case to resolve itself in correspondence and then reaching for the Tax Court on day 95. In Florida there is no appellate decision saying a late petition can be heard, and the Tax Court's own default is that it cannot.
The honest limit is that the law here is moving. Three federal appeals courts have said this deadline can be extended in extraordinary circumstances, two have said the opposite, and the court that covers Florida has said nothing. Nobody can tell you today how the Eleventh Circuit will rule, and the only petition that does not depend on the answer is the one filed inside the period.
Kevin D. Klagge, Esq., admitted in Florida since 2012. Any case described is a decision of a court rather than a matter handled by this firm. General information rather than advice on your situation.
Updated on September 16, 2026. Reviewed by Kevin D. Klagge, Esq., Fla. Bar No. 99502. Attorney Kevin Klagge represents families, businesses, and international clients in estate and tax planning, business structuring, and international law, with a focus on Florida legal tools. He litigates estate and business issues in court. This article is general information about federal law, not legal or tax advice, and does not create an attorney-client relationship. Deficiency and collection outcomes depend on your own facts, your transcripts and IRS procedures that change. The last day printed on your notice controls over any general description here. Past results do not guarantee a similar outcome.
More Guides on International Tax Planning
This guide is part of International Tax Planning.