Got a "Notice of Deficiency" From the IRS? Your 90 Days to Petition Tax Court

A Notice of Deficiency from the IRS — often called a "90-day letter" — can be alarming. It looks like a bill, but it isn't one yet. It's actually your ticket to challenge the IRS before you have to pay. The catch: it starts a strict deadline you cannot afford to miss.

What the notice really is

Before the IRS can formally assess most additional income tax, it must send you a Notice of Deficiency explaining the proposed change. This notice is what gives you the right to take the dispute to the United States Tax Court — the one court where you can contest the tax without paying it first.

The 90-day clock is the whole ballgame

You generally have 90 days from the date the notice is mailed to file a petition with the Tax Court (150 days if the notice is addressed to you outside the United States). This deadline comes from Internal Revenue Code section 6213(a), and courts treat it as jurisdictional — meaning if you file even one day late, the Tax Court generally cannot hear your case, no matter how good it is. The notice itself usually prints the last day to file. Trust that date and don't wait.

Petition goes to the court — not the IRS

The petition is filed with the Tax Court, not mailed back to the IRS. Filing on time preserves your right to have a judge review the IRS's position before any assessment or collection.

What happens if you do nothing

If the 90 days run out with no petition, the IRS can assess the proposed tax and move to collect it — with interest and penalties. At that point your options are narrower and generally more expensive (for example, paying and then suing for a refund).

You still have room to resolve it

Filing a timely petition doesn't lock you into a courtroom fight. Many Tax Court cases settle with IRS Appeals afterward. But the petition is what preserves your leverage and keeps the case out of immediate collection.

When to talk to a lawyer

Because the 90-day deadline is unforgiving, a Notice of Deficiency is one of those letters to act on right away. Someone who handles Tax Court matters can confirm the deadline, evaluate the IRS's position, and file a proper petition to protect your rights.

Holding an IRS notice with a deadline? Ask a legal question.