The IRS Notice of Deficiency (CP3219A): What It Means and Exactly What to Do Next

Nobody enjoys IRS mail, and a "Notice of Deficiency" has the scariest name in the stack. Here's what it actually is, from someone who answers these for a living: the IRS received information from a third party — a 1099, a W-2, a broker statement — that doesn't match what's on your return, and this notice (formally the CP3219A) is their proposed correction.

Two things to hold onto. First, this is not an audit, and it isn't necessarily bad — depending on the mismatch, the correction can even run in your favor. Second, and this is the part that matters: the notice starts a hard legal deadline. It's called the "90-day letter" for a reason — you generally have 90 days from the notice date to petition the United States Tax Court, and the court will not hear a petition filed late. Everything below happens inside that window.

If you agree with the change

Read the notice's calculation carefully. If it's right, sign the enclosed Form 5564 (the waiver) and return it to the address on the notice. Then either pay the new balance or — if the correction went your way — wait for your money. If you can't pay in full, that's a solvable, routine problem: installment agreements exist, and in genuine hardship cases an Offer in Compromise can settle the debt for less. Owing money you can't immediately pay is a payment-terms conversation, not a crisis.

If you don't agree

You have real options, in escalating order:

Send documentation. If you have records that resolve the mismatch, mail them with Form 5564 to the address on the notice. Critical caveat: doing this does not pause or extend your 90-day Tax Court deadline. If the IRS is still "reviewing" as the deadline approaches, file the petition anyway to preserve your rights.
Fix it at the source. If the third party reported wrong — a client double-issued a 1099, a broker misreported basis — get them to file a corrected form. That's often the cleanest kill.
Petition the Tax Court. This is your right, it doesn't require paying the disputed amount first, and filing it is what keeps the IRS from assessing while the dispute is decided.

If identity theft is behind it

Income you never earned, reported under your SSN, is a different track: file Form 14039 (Identity Theft Affidavit) and work the IRS identity-theft process. As a federally licensed tax practitioner, this is territory where representation earns its fee fastest.

One more thing

If the mismatch was a legitimate miss on your end — a late-arriving 1099 you forgot — check whether the same item infects other years, and amend before the IRS finds it there too.

A Notice of Deficiency handled correctly is usually a contained, boring problem. Handled late, it becomes an assessed tax with collections behind it. If one is sitting on your desk, attach it with the paperclip in the chat — we scope and quote the response in writing after intake, and the clock matters. The free sample chapter of my Guide is at /book.