How to use the tax appeal deadline calculator
The United States has no tax tribunal that mirrors Korea's Tax Tribunal, so a federal tax dispute follows a different map: an IRS examination leads to an administrative protest with the independent Office of Appeals, and a statutory notice of deficiency opens a short window to petition the United States Tax Court. Enter the date the notice was mailed and the calculator returns that petition deadline.
How the days are counted — the clock in 26 U.S.C. 6213(a) runs from the date the notice is mailed, not the date it arrives, and the mailing day itself is not counted. If the last day falls on a Saturday, Sunday or legal holiday, 26 U.S.C. 7503 moves the deadline to the next business day; the calculator shows the weekend roll-over, so check holidays separately. Periods stated in years run to the same calendar date, which is why the refund suit line uses an anniversary date rather than a day count.
Legal basis — a taxpayer has 90 days after a notice of deficiency is mailed to petition the Tax Court, or 150 days if the notice is addressed to a person outside the United States (26 U.S.C. 6213(a)), and the IRS may not assess the tax during that period. A suit for refund must be brought within 2 years after the notice of disallowance is mailed (26 U.S.C. 6532(a)). Figures are current as of September 2026.
This calculator is for reference only and is not legal advice. Consult a licensed attorney or CPA about your specific situation.
Frequently asked questions
The period is set by statute and courts treat it strictly, so the safest course is to file early. A late petition normally leaves only the pay-then-sue refund route in district court or the Court of Federal Claims.
An administrative protest to the IRS Office of Appeals is optional but common, and it does not extend the statutory petition period. Whether it fits your case depends on the facts, so talk to a tax professional.