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A CP3219A is the IRS’s formal Notice of Deficiency. It says the agency intends to assess more tax, and it gives you 90 days from the mailing date (150 days if it is addressed to you outside the United States) to challenge that tax in the U.S. Tax Court without paying it first. If you miss that window, the IRS can assess the tax and start collecting. The IRS cannot extend the deadline, and sending the IRS more documents does not pause it.

This guide explains why you received a CP3219A, how the 90-day clock really works, your options, how to file a Tax Court petition, and what to do if the deadline has already passed.

Notice CP3219A is a statutory notice of deficiency issued through the IRS’s Automated Underreporter (AUR) program. That program compares the income on your return with the information returns the IRS receives from employers, banks, brokers, payment apps and crypto exchanges, such as Forms W-2, 1099-NEC, 1099-K, 1099-B and 1099-DA.

When those numbers don’t match, the IRS usually sends a CP2000 first. That notice proposes changes and invites you to agree or explain. If you don’t respond to the CP2000, or the IRS doesn’t accept your explanation, the next step is the CP3219A.

The IRS and the Taxpayer Advocate Service often call it a “90-day letter” or your “ticket to the Tax Court.” That second name is the important one. The Tax Court is the only court where you can dispute a federal tax bill before paying it, and the notice of deficiency is what opens that door.

A few related notices are easy to confuse with it:

• Letter 3219 is the notice of deficiency the IRS usually sends after a mail or field audit.
• CP3219N is sent when the IRS prepares a return for you because you didn’t file one.

All three carry the same 90-day Tax Court deadline. Only the route that led to them differs.

Most CP3219A notices follow a predictable sequence:

1. You file a return. Some income is missing or reported differently from a third party’s records, such as a 1099 from a client or a brokerage sale.
2. The IRS sends a CP2000. It proposes additional tax and asks you to agree or disagree, usually within 30 days.
3. The issue isn’t resolved. You didn’t respond, or the IRS reviewed your response and still disagrees.
4. The IRS mails a CP3219A. It is sent by certified or registered mail to your last known address and lists the last day to petition the Tax Court.
5. After the deadline, the IRS assesses. If no petition is filed, the tax, penalties and interest are assessed, and balance-due notices follow, starting with a CP14.

The CP3219A is the last point at which you can dispute the tax in court before it becomes a bill.

The deadline comes from Internal Revenue Code § 6213(a). The rules behind it are stricter than many people expect.

• The clock starts on the mailing date, not the day you open it. A notice mailed to your last known address is generally valid even if you never received it. If you moved without updating your address with the IRS, the clock may already be running.
• The date printed on the notice protects you. The CP3219A must state the last day to file a petition. A petition filed by that date is treated as timely, even if the IRS calculated it incorrectly.
• Weekends and holidays roll forward. If the last day falls on a Saturday, Sunday or legal holiday in Washington, D.C., the deadline moves to the next business day.
• It is 150 days if the notice is addressed to you outside the United States.
• The IRS cannot extend it. The IRS says plainly that once a CP3219A is issued, it cannot give you more time to respond or petition.
• Talking to the IRS does not stop the clock. Sending documents to the AUR unit, calling the number on the notice, or requesting reconsideration does not pause the Tax Court deadline. You can do those things, but file your petition on time anyway.

For decades, courts treated the 90-day deadline as “jurisdictional,” meaning a single day late was fatal no matter the reason. After the Supreme Court’s 2022 decision in Boechler v. Commissioner, which involved a different Tax Court deadline, that view has been challenged.

Several federal appeals courts, including the Second, Third, Sixth and Eighth Circuits, have since held that the § 6213(a) deadline is not jurisdictional and can, in rare cases, be extended through “equitable tolling.”

The First Circuit ruled in 2026 that it is not jurisdictional but still cannot be extended. The Tax Court itself has held the deadline is jurisdictional. In late September 2026, the Senate also passed a bill that would allow equitable tolling, but it is not yet law.

The practical message for California taxpayers is simple: treat the date on your notice as absolute. Equitable tolling, where it is available at all, requires extraordinary circumstances and diligent effort. It is a last-resort argument, not a plan.

Read the whole notice, not just the amount due. A CP3219A typically includes:

• the tax year and the proposed increase in tax
• the specific items changed, such as unreported wages, 1099 income, investment sales or retirement distributions
• any proposed penalties, often the 20% accuracy-related penalty
• the last date to petition the Tax Court
• Form 5564, Notice of Deficiency – Waiver, which you sign only if you agree

The amounts may differ from your earlier CP2000. Interest keeps accruing, and the IRS may have accepted part of an earlier response. Compare every line with your return and your own records.

You have three realistic paths.

1. Agree and sign Form 5564.

If the IRS is right, signing the waiver lets the IRS assess the tax right away, which stops some interest from building. You can pay in full or wait for a bill. If you can’t pay, you can then request a payment plan.

2. Disagree and petition the Tax Court.

This is the main way to protect your rights. Filing a petition stops the IRS from assessing or collecting the disputed tax while the case is pending. In most cases, filing also opens the door to settlement talks with the IRS Independent Office of Appeals, which resolves many Tax Court cases without a trial.

3. Do nothing.

After the deadline passes, the IRS assesses the full proposed amount, including penalties and interest, and moves to collection. This is the most expensive option, and the most common one.

There is also a fourth path for people who prefer to pay first: pay the tax, file a refund claim, and if the IRS denies it, sue in federal district court or the Court of Federal Claims. That route requires paying the full amount up front, so it is rarely the first choice.

Filing a petition is less complicated than most people expect, but every detail matters.

1. Use the right form. File a petition with the S. Tax Court electronically through its DAWSON system, or by mail to the court in Washington, D.C. Do not send the petition to the IRS. A petition mailed to the IRS is not filed with the court.
2. Attach the notice. Include a copy of the CP3219A.
3. Explain what you dispute. State each adjustment you disagree with and the facts behind your position.
4. Choose a trial location. The Tax Court holds trials in cities across the country. California has several, including Los Angeles, San Diego and San Francisco.
5. Pay the filing fee. The fee is $60. You can ask the court to waive it if you cannot afford it.
6. Decide on a small tax case. If the amount in dispute, including penalties, is $50,000 or less for a given tax year, you can elect the simplified “S case” procedure. It is less formal and faster, but the decision generally cannot be appealed.

For an e-filed petition, the Tax Court treats it as timely if it is submitted by 11:59 p.m. Eastern time on the due date. For California filers, that is 8:59 p.m. Pacific. Don’t wait until the last evening.

If no petition is filed in time, the IRS assesses the tax. You’ll receive balance-due notices, and an unpaid balance can lead to a CP504, a federal tax lien, and eventually bank levies or wage garnishment.

You are not out of options, but they get narrower:

• Audit reconsideration. If you have new documentation the IRS never considered, you can ask it to reopen the assessment.
• Pay and seek a refund. Pay the tax, file a refund claim, and if denied, sue in district court or the Court of Federal Claims.
• Offer in Compromise based on doubt as to liability. This is available when there is genuine doubt that you owe the tax.
• Collection alternatives. If the tax is correct but unaffordable, installment agreements, Currently Not Collectible status, and other options may apply.

You may also be able to challenge the assessment if the notice was never properly mailed to your last known address. That can matter if you moved and the IRS sent it to an old address.

For Californians, a federal deficiency rarely stays federal. When the IRS changes your federal income, California generally requires you to report the change to the Franchise Tax Board within six months of the final federal determination. If you don’t, the FTB can issue its own assessment, often months later and with additional interest.

If you settle a Tax Court case, or let a CP3219A become final, plan for the state side at the same time. Coordinating both can prevent a second surprise bill, and in some cases can reduce what you owe California.

• Responding only to the IRS address on the notice. That response does not stop the Tax Court deadline.
• Assuming the CP2000 response “took care of it.” If you received a CP3219A, the IRS did not fully accept it.
• Signing Form 5564 to make it go away. Signing means you agree, and you give up your right to go to Tax Court.
• Waiting for the money to pay before acting. The Tax Court does not require you to pay first. That is the whole point of the notice.
• Forgetting about penalties. The accuracy-related penalty can often be challenged separately, even when the underlying income is correct.

Is a CP3219A a bill?

No. It is a formal notice of a proposed tax increase. The tax is not assessed until the deadline passes or the case is resolved.

Can the IRS give me more time?

No. Once the notice is issued, the IRS cannot extend the time to petition the Tax Court.

Do I need a lawyer to file a Tax Court petition?

No, many taxpayers file on their own. But representation by a tax attorney often leads to better settlements with IRS Appeals, especially when penalties or larger amounts are involved.

What if I’m out of the country?

If the notice is addressed to you outside the United States, you generally have 150 days instead of 90.

Will California also bill me?

Often, yes. Federal changes generally must be reported to the FTB, which may assess its own tax.

The date on your notice is the most important in your case. Leading Tax Group’s team includes a former IRS appeals officer, a former IRS tax attorney, and tax attorneys who handle the FTB side of the same dispute. We can review your notice, file a timely Tax Court petition, and negotiate with IRS Appeals while coordinating your California exposure. Book a free, confidential consultation or call 800-900-4250.