Which notice you are holding
The number on the letter tells you which part of the IRS produced it. It does not tell you anything about how serious it is, because they are all the same instrument.
| Number | Where it comes from |
|---|---|
| Letter 531 | "issued to taxpayers whose audits were conducted in person" |
| Letter 3219 | "sent to taxpayers whose IRS audit was conducted by mail" |
| CP3219A | Follows the underreporter (document-matching) process |
| CP3219N | Where the IRS prepared a return on your behalf |
| Letter 3219B | The business underreporter version — Form 1120 or Form 1041 |
Source: Taxpayer Advocate Service, “90 Day Notice of Deficiency” and “Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond,” last updated 12 May 2026; IRS, “Understanding your CP3219A notice” and “Understanding your Letter 3219B.” Read 6 September 2026.
We publish this table because nobody else does, and because a reader who searches “Letter 3219” and finds only CP3219A pages concludes they have the wrong document. The IRS does not publish an “Understanding your notice” page for Letter 531 or Letter 3219 — we checked those and four others, against seven controls that do have pages. What exists is the Taxpayer Advocate Service's notice pages and the statute.
One practical consequence of the split. The waiver form enclosed differs: a CP3219A encloses Form 5564, a Letter 3219B encloses Form 4089. Both are called a Notice of Deficiency – Waiver, and neither is downloadable — they arrive with the notice. If yours is missing from the envelope, call the number on the notice rather than searching for it.
What a Notice of Deficiency is
It is the letter that gives you the right to dispute a proposed tax in court before it can be assessed against you. The Taxpayer Advocate Service:
“Because this notice provides you with the right to challenge the proposed adjustment in the Tax Court without first paying the proposed adjustment, the statutory notice of deficiency is often considered ‘your ticket to the Tax Court.’”
“Without first paying” is the whole point. Every other route to a court on a tax dispute means paying first and suing for a refund afterwards.
How it is delivered, and why that matters. The IRS is required to send it by certified or registered mail to your last known address — which is “generally the address that appears on your most recently filed and properly processed tax return unless the IRS is given clear and concise notification of a different address.” Section 6212(b)(1) makes a notice mailed to that address sufficient even where the taxpayer has died, is under a legal disability, or, for a corporation, has ceased to exist. A notice properly mailed works whether or not it was read, which is why a Form 8822 change of address is not an administrative nicety.
Your clock
90 days to file a petition, 150 if the notice is addressed to you outside the United States. File by the date printed on the notice.
The statute:
“Within 90 days, or 150 days if the notice is addressed to a person outside the United States, after the notice of deficiency authorized in section 6212 is mailed (not counting Saturday, Sunday, or a legal holiday in the District of Columbia as the last day), the taxpayer may file a petition with the Tax Court for a redetermination of the deficiency.” — 26 U.S.C. 6213(a)
And the sentence that makes the printed date the safe one:
“Any petition filed with the Tax Court on or before the last date specified for filing such petition by the Secretary in the notice of deficiency shall be treated as timely filed.”
The period runs from mailing; the printed date is a floor. Filing by the date printed is always timely. It cannot shorten the statutory period, so if the printed date looks earlier than 90 days from the postmark, that is a question worth asking before the earlier of the two arrives — not after.
Three mechanics that decide cases:
- It goes to the Court, not to the IRS. “you must send your petition to the United States Tax Court (not the IRS).”
- Electronically filed, by 11:59 p.m. Eastern Time on the last day. “Petitions received after this time may be untimely and your case may be dismissed.”
- Weekend and DC holiday roll-over. If the 90th or 150th day falls on a Saturday, Sunday or DC legal holiday, the next business day is timely.
And the one that catches people who are trying hard. Sending the IRS more information, and getting a reply, does not extend anything. The IRS says it about its own version of this notice: “We can't extend the time you have to file a petition with the U.S. Tax Court if you choose to do so.”
Sources: 26 U.S.C. 6212, 6213(a); Taxpayer Advocate Service, “90 Day Notice of Deficiency”; United States Tax Court petitioner guidance. All read 6 September 2026.
What is protected while this runs
Nothing can be assessed and nothing can be levied on this deficiency until the period expires — and if you petition, until the Tax Court is finished with it.
“…no assessment of a deficiency … and no levy or proceeding in court for its collection shall be made, begun, or prosecuted until such notice has been mailed to the taxpayer, nor until the expiration of such 90-day or 150-day period, as the case may be, nor, if a petition has been filed with the Tax Court, until the decision of the Tax Court has become final.” — 26 U.S.C. 6213(a)
The same subsection provides that collection begun in breach of that bar “may be enjoined by a proceeding in the proper court, including the Tax Court.”
The limits, stated in the same breath because they belong there. It protects this deficiency. A balance already assessed for another year keeps moving on its own schedule and this notice does nothing about it. And the statute names its own exceptions — sections 6851, 6852 and 6861, covering termination and jeopardy assessments — which are unusual and are not theoretical.
Two things about the number that pull in opposite directions
The figure may be lower than the one you saw before. The IRS explains why, and it is jurisdictional rather than generous: “The amounts due on the enclosed Form 5564, Notice of Deficiency – Waiver, may not match your prior notice amount due. This is because you can't challenge all items in U.S. Tax Court.”
And the figure will be lower than what you eventually pay. The Taxpayer Advocate Service: “Sometimes, but not always, the IRS includes penalties in the notice of deficiency, but does not include interest. The IRS will ultimately send a bill for the tax due, interest, and any applicable penalties.”
Both are true at once. Neither is a trick, and knowing both is the difference between planning and being surprised twice.
What happens if you do nothing
The deficiency is assessed, a bill follows, and collection begins. The dispute about whether the number is right becomes a dispute about how to pay it — and those are different cases with different tools.
There is a route back, and it has a condition that runs against instinct. Audit reconsideration lets you ask the IRS to look again where you have information it has not considered. The Taxpayer Advocate Service names it for exactly this situation: “If you miss the deadline and you have additional information that could change the tax liability assessed, you may request an audit reconsideration.”
But: “You can only request audit reconsideration if the assessed tax liability remains unpaid. If you've already paid the tax, you'll need to file an amended return (Form 1040X) to claim a refund.” — IRS, audit reconsideration guidance, read 6 September 2026.
Paying the bill to make it stop is what closes that door. The refund route that remains has its own deadline, measured from dates specific to your account. What audit reconsideration is and what it needs →
What to do in the next 90 days
1. Today: find the last date to petition, printed on the notice, and write it somewhere that is not the envelope. Nothing else on this page has to happen today.
2. Read the audit report enclosed with it. The Taxpayer Advocate Service: “You should review the complete audit report enclosed with your letter.” The notice must “describe the basis for, and identify the amounts of, proposed assessment” — so the reasoning is in the envelope, whether or not it is easy to follow.
3. Decide between three things. Sign the waiver and end it. File a petition and keep the argument alive. Or send the IRS information it has not seen — while separately protecting the filing date. The third is the one people get wrong, because it looks like the sensible middle and is only sensible if the date is protected.
4. If you petition, the practical facts are small. The filing fee is $60 — United States Tax Court, “Starting a case” — payable by check, money order or Pay.gov, and the Court will waive it “if a petitioner establishes to the satisfaction of the Tax Court an inability to pay” — on an application that “requires detailed information and must be signed under penalty of perjury.” The Court publishes a petition kit and encourages electronic filing through its DAWSON system.
5. Consider the simplified track, and consider what it costs. Where the deficiency in dispute is $50,000 or less for any one taxable year — a figure that includes penalties — you may elect to have the case heard as a small tax case, if the Court concurs. The trade is that the decision “shall not be reviewed in any other court and shall not be treated as a precedent for any other case.” No appeal, for either side.
6. Do not stop filing and paying current years. A petition on one year says nothing about the next one, and a new balance while this is pending narrows what can be arranged later.
The hard part is deciding whether to file, not filing. The form is a form. Whether the point in dispute is one a court is likely to move needs the report, the transcripts, and an honest reading of what the IRS actually asserted — which is not the same as an honest sense that the examiner was unreasonable.
