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Quick Answer: When a taxpayer disagrees with an IRS-proposed tax assessment and wants to contest it before paying, they can file a petition with the U.S. Tax Court within 90 days of receiving a Notice of Deficiency (150 days if addressed outside the U.S.). The case then proceeds through pleadings, an IRS Appeals settlement attempt, discovery, and — if unresolved — a trial before a Tax Court judge, who issues a written opinion deciding the disputed amount.

The U.S. Tax Court is a federal court that hears disputes between taxpayers and the IRS over proposed tax deficiencies, without requiring the taxpayer to pay the disputed amount first. This is what distinguishes it from the two other forums available to contest a tax liability: federal district court and the U.S. Court of Federal Claims, both of which generally require the taxpayer to pay the assessed tax in full and then sue for a refund.

For most individuals and businesses contesting the outcome of an IRS audit, Tax Court is the only realistic option that doesn’t require paying first — which is a large part of why it’s the forum most tax controversy cases actually go through.

The court is based in Washington, D.C., but its judges travel on a regular circuit to hear cases in cities across the country, so most petitioners never need to travel to D.C. for their own case.

Tax Court exists to give taxpayers an independent forum — separate from the IRS itself — to challenge a proposed assessment. The judges are not IRS employees; they’re presidentially appointed, and the court’s role is to review the facts and apply the law to reach a decision that’s binding on both sides, subject to appeal.

Any taxpayer — individual or business — who receives a Notice of Deficiency (sometimes called a “90-day letter”) after an audit or IRS review, and who disagrees with the IRS’s determination, has the right to petition Tax Court.

This covers income tax deficiencies, accuracy-related and other penalties assessed alongside a deficiency, and several other categories of IRS determination specified by statute, including certain collection due process and innocent spouse determinations. It does not cover every kind of tax dispute — some issues (for example, disputes over an already-paid liability) belong in district court or the Court of Federal Claims instead.

In most Tax Court cases, the taxpayer bears the initial burden of proving the IRS’s determination is incorrect. There’s a narrow statutory exception (IRC § 7491) that can shift the burden to the IRS on factual issues, but only if the taxpayer has cooperated with the IRS and maintained adequate records — which in practice means the exception rarely changes how a well-prepared case is actually argued. The practical takeaway is the same regardless of who technically carries the burden: the taxpayer’s documentation is what decides the case.

1. Notice of Deficiency issued. The IRS sends written notice of the proposed additional tax after an audit concludes without agreement. This notice states the exact deadline for filing a petition.
2. 90-day window to petition. The taxpayer must file a petition with the Tax Court within 90 days (150 days if the notice is addressed to a person outside the United States). This deadline is jurisdictional — the court generally cannot hear a case filed even one day late, and missing it forecloses the ability to contest the amount before paying.
3. IRS answers the petition. IRS counsel (not the original examining agent) files a formal answer, and the case is entered onto the court’s docket, typically for a trial session in the petitioner’s home city several months to over a year later.
4. IRS Appeals review (often). A large share of petitioned cases are referred back to IRS Appeals — the same independent settlement function available before litigation — for another attempt at resolution, since Appeals retains settlement authority even after a case has been filed in court.
5. Discovery and pretrial preparation. Both sides exchange documents, respond to information requests, and are required to stipulate to facts and documents that aren’t genuinely in dispute, which narrows what actually needs to be argued at trial.
6. Pretrial memorandum and calendar call. Shortly before the assigned trial session, both sides file memoranda summarizing their positions, and the case is called on the court’s trial calendar for that city.
7. Trial (if still unresolved). A significant share of petitioned cases settles before ever reaching this stage. Cases that don’t settle are tried before a single Tax Court judge — without a jury — usually in whichever city on the court’s circuit is nearest the taxpayer.
8. Opinion and decision. The judge issues a written opinion deciding the disputed issues. Cases handled under the simplified “S case” procedure get a decision that isn’t appealable and doesn’t set precedent; regular-procedure decisions can be appealed to the U.S. Court of Appeals for the taxpayer’s circuit.

Taxpayers with a disputed amount of $50,000 or less for any one tax year or period can elect the simplified “S case” procedure. It uses more relaxed rules of evidence, is generally faster and less costly to litigate, and doesn’t require the level of formal briefing a regular case does.

The tradeoff is that an S case decision can’t be appealed by either side and doesn’t create legal precedent — it resolves that one case only. Taxpayers with larger disputes, or whose case turns on a legal question they may want preserved for appeal, use the regular procedure instead.

Having clerked at the U.S. Tax Court before representing taxpayers before it, Elizabeth Nelson notes that outcomes are shaped far more by what happened during the audit and Appeals stages than by anything that happens at trial itself. A few patterns stand out from that vantage point:

• The factual record is largely fixed by the time of trial. The documents, stipulations, and positions taken at the audit and Appeals stages become the foundation the court works from — there’s limited room to introduce a materially different case once litigation is underway.
• Judges see recurring fact patterns. What feels like a unique set of circumstances to an individual taxpayer is often one the court has evaluated many times before, in similar form. That familiarity tends to make outcomes more predictable than taxpayers expect, which cuts both ways — it can work against a weak case just as easily as it can support a well-documented one.
• Settlement remains available throughout. Because Appeals retains authority to settle a case even after a Tax Court petition is filed, many cases resolve well short of trial once both sides have a clearer view of the evidence through discovery.

Timing varies widely by court location and case complexity, but it’s common for a petitioned case to take one to two years from filing to resolution, longer if it proceeds to trial and a written opinion rather than settling. Cases using the S case procedure typically move faster than regular-procedure cases.

• Confirm the 90-day (or 150-day) deadline immediately — it runs from the date printed on the notice, not the date it’s received or reviewed.
• Gather the documentation underlying the disputed items before the petition is filed, since this becomes the foundation of the case record.
• Consider whether the case is likely to qualify for the S case procedure, and whether that tradeoff (speed and cost vs. appeal rights and precedent) fits the situation.
• Consult a tax attorney before the deadline passes — once it does, the option to contest the amount before payment is generally gone, and the remaining paths (pay and sue for a refund, or negotiate a collection resolution) are usually more expensive and slower.

1. Do I have to go to Tax Court if I disagree with an IRS audit?

No. A taxpayer can also request an IRS Appeals conference before a Notice of Deficiency is even issued, or pay the assessed amount and pursue a refund suit in district court or the Court of Federal Claims instead. Tax Court is the only option that doesn’t require paying first.

2. Can a Tax Court case settle before trial?

Yes — most petitioned cases resolve through settlement with IRS Appeals or IRS counsel rather than going to trial.

3. Do I need an attorney to petition Tax Court?

Taxpayers can represent themselves (“pro se”), but Tax Court practice involves specific procedural, evidentiary, and briefing rules, and representation is generally recommended for anything beyond a straightforward small-dollar case.

4. What happens if I miss the 90-day deadline?

The Tax Court generally loses jurisdiction to hear the case. The assessment becomes final, and the remaining options are paying the tax and filing a refund claim, or addressing the liability through IRS collection alternatives such as an installment agreement or offer in compromise.

5. Is a Tax Court case public record?

Yes. Tax Court filings and opinions are generally public, though certain sensitive information can be filed under seal or redacted in limited circumstances.

6. Can I still negotiate with the IRS after filing a Tax Court petition?

Yes — filing a petition doesn’t end settlement discussions. IRS Appeals and IRS counsel routinely continue working toward a resolution throughout the litigation process, right up until trial.