You generally have 90 days from the mailing date printed on an IRS Notice of Deficiency to respond, and how to respond to an IRS Notice of Deficiency comes down to three real choices: sign the waiver and accept the amount, ask the IRS Independent Office of Appeals to reconsider, or file a petition with the United States Tax Court to challenge the deficiency before you pay it. The notice arrives as Letter 3219 or notice CP3219N and is the IRS’s final determination that you owe additional tax, penalties, or interest. Miss the deadline and the IRS can assess the full amount without further review.
Read the Notice Against Your Return
The first page of the notice states the determination date and the total the IRS says you owe, including penalties and interest. An “explanation of items” section lists each income, deduction, or credit adjustment the IRS made. Compare those figures line by line against the return you filed for the year in question.
Pull your records for that year — W-2s, 1099s, bank statements, and receipts for any deduction the IRS is challenging. If the notice came from an automated underreporter inquiry, where the IRS’s third-party data didn’t match what you reported, brokerage statements and K-1s matter most. A clean side-by-side of the IRS’s numbers against your documents is what tells you whether to agree, negotiate, or fight.
How the 90-Day Deadline Actually Runs
The 90-day clock starts on the date the IRS mailed the notice, not the date you opened it. The IRS sends it by certified mail to your last known address, and actual receipt is not required for the deadline to apply. If the letter comes back unclaimed or refused, the 90 days still run from the mailing date.
If the last day falls on a Saturday, Sunday, or a legal holiday in the District of Columbia, you get the next business day.1eCFR. 26 CFR 301.6213-1 – Restrictions Applicable to Deficiencies; Petition to Tax Court If the notice is addressed to a person outside the United States, or you are outside the country when it is mailed, the period is 150 days instead of 90.2Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court The IRS cannot extend either deadline for any reason.3Taxpayer Advocate Service. 90-Day Notice of Deficiency
Agreeing and Signing the Waiver
If the IRS’s numbers hold up against your records, or you simply want the matter closed, sign the waiver included with the notice and mail it to the address on the notice. The package typically contains Form 4089-B or Form 5564-A, both titled Notice of Deficiency — Waiver.4Internal Revenue Service. 4.8.9 Statutory Notices of Deficiency Enter your name and Social Security number exactly as they appear on the notice, confirm the amount you accept, and send it by certified mail with return receipt so you have proof of the date.
Signing the waiver ends the 90-day period and keeps the case out of Tax Court. The IRS assesses the tax and sends a bill for the deficiency plus accrued interest and penalties. From there, you are in collection.
If You Cannot Pay in Full
A short-term plan gives you up to 180 days to pay the balance with no setup fee. A long-term installment agreement lets you pay monthly. If your combined tax, penalties, and interest are $50,000 or less, you can apply online; setup fees run from $22 for automatic monthly payments applied for online up to $178 for non-direct-debit agreements applied for by phone or mail, with reduced or waived fees for low-income taxpayers.5Internal Revenue Service. Payment Plans; Installment Agreements Interest and penalties keep accruing on the unpaid balance.
Requesting an Appeals Conference
You can ask the IRS Independent Office of Appeals to look at the case. Appeals officers can settle based on the “hazards of litigation” — how uncertain the outcome would be at trial — which means they can cut a proposed deficiency even when the examination division won’t.
Send a written protest to the IRS address on the letter that explained your appeal rights, not directly to Appeals. For disputes of $25,000 or less per tax period, file Form 12203, Request for Appeals Review, listing the items you disagree with and your reasons. Larger disputes require a formal written protest. The deadline for the protest is generally 30 days from the date on the letter offering appeal rights.6Internal Revenue Service. Preparing a Request for Appeals
Requesting Appeals does not pause the 90-day Tax Court deadline. If you want to protect your right to go to Tax Court while Appeals looks at the case, file the petition inside the 90 days anyway. The Appeals discussion can continue alongside the court case.
Filing a Petition in U.S. Tax Court
The main reason to file in Tax Court is that you do not have to pay the disputed amount first. You contest the deficiency before the IRS can collect.2Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court
File within the 90-day period (or 150 days if you qualify) from the mailing date. You can file electronically through DAWSON, the court’s online system, or mail a paper petition to the United States Tax Court, 400 Second Street, NW, Washington, DC 20217.7United States Tax Court. How to eFile a Petition Do not file both ways.
Use Form 2, the court’s simplified petition. Check the box for disputing a Notice of Deficiency, state the exact dollar amounts you contest (including penalties), and attach a copy of the notice.8United States Tax Court. Tax Court Form 2 – Petition (Simplified Form) Do not attach returns, receipts, or evidence; those come later. The filing fee is $60, and the court accepts an Application for Waiver of Filing Fee if you cannot afford it.9United States Tax Court. Court Fees
Small Tax Case Election
If the disputed amount, including penalties, is $50,000 or less for any single year, you can elect to have the case handled as a “small tax case,” or S case. These use simpler procedures and generally move faster.10United States Tax Court. Filing a Case in the United States Tax Court The tradeoff: neither side can appeal a small tax case decision, and the opinion cannot be cited as precedent.11United States Tax Court. Guidance for Petitioners: Things That Occur After Trial If your case turns on a legal issue you might want to appeal, file as a regular case.
Mailing a Paper Petition
If you mail the petition, the postmark date counts as the filing date under the “timely mailed, timely filed” rule. Besides the U.S. Postal Service, only certain IRS-designated private delivery services qualify, including specific offerings from DHL Express, FedEx (such as FedEx Priority Overnight and FedEx Standard Overnight), and UPS (such as UPS Next Day Air and UPS 2nd Day Air). Standard ground shipping does not qualify.12Internal Revenue Service. Private Delivery Services (PDS) Ask the carrier for written proof of the mailing date.
If the Deficiency Comes From a Joint Return
When the understated tax on a joint return is attributable to your spouse or former spouse, innocent spouse relief may apply. You must show that you filed jointly, that the understatement came from your spouse’s erroneous items, that you did not know and had no reason to know about it when you signed the return, and that holding you liable would be unfair under the circumstances.
File Form 8857, Request for Innocent Spouse Relief, with the IRS (not the Tax Court) as soon as you learn of the liability. If you also received a Notice of Deficiency, file a Tax Court petition within the 90 days and raise innocent spouse relief as a defense in the petition. The 90-day deadline does not pause while the IRS considers Form 8857, so file both.13Internal Revenue Service. Instructions for Form 8857, Request for Innocent Spouse Relief
When the Notice Itself Was a Mistake
If the notice went to the wrong taxpayer, covered the wrong year, or was mailed prematurely, either side can propose rescinding it. Both you and the IRS must sign Form 8626, Agreement to Rescind Notice of Deficiency, and the IRS’s decision to rescind is discretionary.14Internal Revenue Service. 8.2.2 Statutory Notice of Deficiency Cases Rescission is only available before the 90-day or 150-day deadline expires and before you file a Tax Court petition. Once rescinded, the IRS may issue a corrected notice later if a deficiency still exists.
If the 90 Days Have Already Passed
If the period expires with no petition filed, the IRS assesses the full deficiency and begins collection. You lose the ability to contest the amount in Tax Court before paying, but two options remain.
Audit Reconsideration
If you have new information — documents you didn’t previously provide or evidence of an IRS error — you can request an audit reconsideration. IRS Publication 3598 explains the process.3Taxpayer Advocate Service. 90-Day Notice of Deficiency It is an administrative remedy, not a right, and the IRS can decline.
Refund Suit
The other route is to pay the assessed tax (or the portion you dispute), file a formal refund claim with the IRS, and, if the IRS denies the claim or does not act within six months, sue for a refund in a U.S. District Court or the U.S. Court of Federal Claims.15Office of the Law Revision Counsel. 26 USC 7422 – Civil Actions for Refund Unlike Tax Court, these courts require you to pay first. A district court refund suit also allows a jury trial, which Tax Court does not.
Free Help if You Qualify
Low-Income Taxpayer Clinics, funded through IRS grants, can represent you before the IRS or in Tax Court for free or for a small fee. Eligibility generally requires income below a set threshold and a dispute typically under $50,000. The IRS keeps a state-by-state directory of clinics on its website.16Internal Revenue Service. Low Income Taxpayer Clinics