Key Takeaways Letter 3219 is the Statutory Notice of Deficiency (also called the "90-day letter"), representing the IRS's final determination that you owe additional tax You have exactly 90 days (150 days if outside the U.S.) from the date of the letter to file a petition with the U.S. Tax Court If you do not petition Tax Court within the deadline, the IRS will assess the deficiency and begin collection — and you lose your right to judicial review before paying Filing a Tax Court petition does not require you to pay the disputed tax first — this is a critical advantage Professional representation is essential for Tax Court proceedings due to the complexity of the rules and the stakes involved What Is IRS Letter 3219? IRS Letter 3219, formally known as the Statutory Notice of Deficiency, is one of the most important documents in tax law. Often referred to as the "90-day letter," it is the IRS's formal and final determination that you owe additional tax for a specific tax year. This letter is typically issued after an audit or examination has been completed and either you did not agree with the results, the appeals process did not resolve the dispute, or you did not respond to earlier proposed adjustments. The Letter 3219 is legally required before the IRS can assess a deficiency (additional tax) against you. Under Internal Revenue Code Section 6212, the IRS must send a statutory notice of deficiency and give you the opportunity to petition the U.S. Tax Court before it can assess the additional tax. This is a fundamental taxpayer protection established by Congress to prevent the IRS from simply adding tax to your account without giving you a meaningful opportunity to dispute it before an independent court. The significance of Letter 3219 cannot...