Quick answer

If you receive a notice of deficiency (a “90-day letter”), request a Tax Court review by filing a petition within 90 days of the date the IRS mailed the notice (150 days if the notice was mailed to you outside the United States). Filing on time preserves your right to contest the IRS determination in court instead of paying first and suing for a refund.

When to choose Tax Court (practical triggers)

  • You receive a formal Notice of Deficiency from the IRS challenging tax, penalties, or proposed adjustments.
  • You prefer to litigate without paying the assessment first (Tax Court lets you litigate before paying).
  • The dispute raises issues where a Tax Court precedent would be helpful for similar taxpayers.

If you have an ongoing administrative appeal with IRS Appeals and it fails, or Appeals issues an adverse decision, Tax Court may be the next step. See our guide on Tax Court vs. Administrative Appeal: Choosing the Right Dispute Path for help deciding the right forum.

Required deadlines and why they matter

  • 90 days from the date the IRS mails the notice of deficiency for U.S. residents (calendar days).
  • 150 days if the notice was mailed to someone outside the United States.
    These deadlines come from federal tax rules intended to limit surprise litigation and are strictly enforced; late petitions are almost always dismissed (see IRC §6213 and U.S. Tax Court practice). For more on the basic filing mechanics, review our article: Tax Court Basics: Filing a Petition After a Notice of Deficiency.

Step-by-step checklist to request a Tax Court review

  1. Read the notice carefully — confirm the tax year(s) and issues the IRS is challenging.
  2. Decide whether to pursue Tax Court or alternatives (IRS Appeals, pay and sue for refund in district court or Court of Federal Claims). See guidance on choosing venues in Tax Court vs. U.S. District Court: Choosing the Right Venue.
  3. Gather supporting documents (returns, schedules, bank records, receipts, correspondence).
  4. Draft the petition — follow the U.S. Tax Court Rules of Practice and Procedure for required content and signature.
  5. File the petition with the U.S. Tax Court before the deadline and serve it on the IRS per the rules.
  6. Consider electing the Small Tax Case (S case) procedure if the amount in dispute is $50,000 or less and you want a faster, simplified process (see Tax Court rules on small tax cases).
  7. If the case proceeds, prepare for discovery, possible settlement discussions, and trial.

In my practice, clients who prepare a concise chronology and label exhibits up front reduce stress during discovery and settlement talks.

Important legal effects to understand

  • Filing a timely petition generally prevents the IRS from assessing and collecting the contested amount while the case is pending (subject to limited exceptions such as jeopardy assessments). This protection comes from the statute governing petitions and assessments (IRC §6213) and Tax Court procedures.
  • Choosing Tax Court means litigating under its rules; you cannot get a jury trial there (unlike district court).
  • Small tax case decisions do not create precedent and cannot be appealed to the U.S. Court of Appeals.

Common mistakes to avoid

  • Missing the 90/150-day filing deadline — courts rarely excuse late petitions.
  • Treating informal phone calls or letters to the IRS as a substitute for filing a petition.
  • Failing to include essential facts or to serve the petition properly on the IRS.
  • Assuming every dispute needs Tax Court; sometimes IRS Appeals or paying and suing for refund is strategically better.

Practical tips and strategies

  • File early — don’t wait until the last day. Mailing issues or service problems can be fatal.
  • Talk to a tax attorney or experienced CPA if the amount, complexity, or penalties are significant. In my 15 years representing taxpayers, early counsel often saves costs and improves settlement outcomes.
  • Keep an organized case file with a timeline, numbered exhibits, and copies of the IRS notice and all correspondence.
  • Consider alternative dispute resolution through settlement conferences; many cases settle before trial.

How long will it take?

Timing varies by case complexity and court docket. Simple cases or small tax cases can resolve in under a year; contested cases with discovery and trial often take 12–24 months or longer.

FAQs (brief)

  • Is there a fee to file a petition?
  • Check the U.S. Tax Court for current filing and motion fee information; some filings or motions may have associated fees under the Court’s schedule.
  • Can I extend the 90-day deadline?
  • No. The 90/150-day deadlines are statutory and generally cannot be extended except in extremely limited, exceptional circumstances.
  • What if I already paid the tax?
  • If you paid and want a refund, your remedy is typically to sue for refund in U.S. district court or the Court of Federal Claims.

Sources and further reading

Professional disclaimer

This article is educational and does not replace personalized legal or tax advice. If you face a notice of deficiency or complicated tax dispute, consult a qualified tax attorney or CPA promptly.