What Is a Statutory Notice of Deficiency?
A statutory notice of deficiency, also known as a 90-day letter, is the IRS formally telling you that they are proposing additional tax. It is sent as Letter 3219 or CP3219A, and it is the most consequential piece of mail the IRS will ever send you.
This letter gives you 90 days (150 days if you are outside the United States) to file a petition with the United States Tax Court. If you file within the deadline, you can challenge the IRS's proposed changes in court without paying the tax first. If you miss the deadline, the IRS assesses the tax and your only option is to pay first and then sue for a refund in district court or the Court of Federal Claims.
Why This Letter Matters More Than Any Other
Tax Court is the only forum where you can dispute a tax liability before paying it. Every other court requires full payment first. For taxpayers who owe tens or hundreds of thousands of dollars, the ability to challenge the IRS without writing a check is often the only realistic option. Losing access to Tax Court can be financially devastating.
When the IRS Sends It
The statutory notice typically comes after an audit or automated underreporter process (AUR) where you either did not respond or disagreed with the proposed changes. It is the final step before the IRS can legally assess the additional tax against you. Before sending it, the IRS usually sends a 30-day letter giving you the chance to appeal within the IRS. The statutory notice means that opportunity has passed.
How the 90 Days Are Counted
The 90-day period begins on the date printed on the notice, not the date you receive it. The IRS mails it to your last known address, and they are not required to confirm delivery. If you moved and did not update your address with the IRS, the notice goes to your old address and the 90 days start ticking. Courts have consistently held that the IRS only needs to mail the notice to the last known address for it to be valid.
What to Do When You Receive One
Contact a tax attorney immediately. Filing a Tax Court petition requires specific legal procedures and formatting. The petition must be filed with the Tax Court in Washington, D.C. (by mail or electronically) and must contain specific information about the disputed items. Filing a defective petition can result in dismissal.
Even if you think you owe the tax, filing a Tax Court petition preserves your right to negotiate. Many cases settle in Appeals after the petition is filed, often at a fraction of the original proposed amount.
If there is one IRS letter you should run to a tax attorney with, it is the statutory notice of deficiency. The 90-day deadline is absolute, and the consequences of missing it are irreversible.