United States Tax Court
When is a US Tax Court deficiency petition due?
A Tax Court deficiency petition normally has a 90-day period from mailing of a US-addressed notice, or 150 days for an outside-US address. The actual notice and Tax Court holiday rule must be checked.
Calculate my deadline- Period
- 90 calendar days
- Trigger
- Mailing of the notice of deficiency
- Rule
- 26 U.S.C. 6213(a); Tax Court Rule 25
26 USC section 6213 and Tax Court Rule 25 checked 07/08/2026
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Calculate your deadline
Enter the date of mailing of the notice of deficiency. See the date, cited rule and counting steps.
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Which date starts the 90-day period?
The period runs from the mailing of the notice of deficiency. The default calculation uses mailing of the notice of deficiency to an address within the United States; other branches use their own trigger.
Count forward from mailing. Confirm the event on the docket or in the service record before entering a date.
Read 26 USC 6213Within 90 days ... after the notice of deficiency authorized in section 6212 is mailed ... the taxpayer may file a petition with the Tax Court for a redetermination of the deficiency.
26 U.S.C. 6213(a); Tax Court Rule 25
This period runs from the specific event in the cited rule. Do not substitute a nearby date such as a hearing, a courtesy copy or the day you first learned of it.
Which date do I enter?How are the 90 calendar days counted?
- Exclude the day of the trigger event.
- Count every following day, including weekends and legal holidays.
- If the last day is a Saturday, Sunday or a legal holiday in the District of Columbia, continue to the next day that is not one of those.
Statutory period with a District of Columbia legal-holiday rule
The calculator applies its dedicated Tax Court and District of Columbia legal-holiday calendar. DAWSON outages and inaccessible filing locations remain manual checks.
Tax Court Rule 25 applies the District of Columbia holiday calendar regardless of where the petitioner lives. Statutory filing periods can also be affected by inaccessibility of the filing location and by the timely-mailing rules.
Read Tax Court Rule 25The calculation gives the ordinary national-rule date. Check relevant holidays, the court’s accessibility and its filing cutoff separately.
Review the filing checklistWhat does a worked calculation look like?
Fictitious example
Assume the mailing of the notice of deficiency on Monday, August 3, 2026 (the notice was mailed to an address within the United States on Monday 3 August 2026. No Tax Court closure or DAWSON outage applies), with no order, motion, extension or local closure affecting the result. The mailing day is excluded. The 90-day period ends on Sunday 1 November, then Tax Court Rule 25 carries the deadline to the next open day, Monday 2 November.
| Step | What is counted | Date |
|---|---|---|
| Trigger | Do not count this day | August 3, 2026 |
| Day 1 | Start counting calendar days | August 4, 2026 |
| Day 90 | Last counted day falls on a weekend or legal holiday | November 1, 2026 |
| Adjusted | Next day that is not a weekend or legal holiday | November 2, 2026 |
Can an order, motion or extension change the deadline?
- Extensions
- The Tax Court cannot extend the statutory filing period. Culp v. Commissioner holds the period non-jurisdictional and equitably tollable in the Third Circuit; the Tax Court continues to treat it as jurisdictional outside that circuit. Never rely on tolling without forum-specific advice.
- Orders and local rules
- A scheduling order, stipulation approved by the court, standing order or local rule can set a different period and controls over the national default.
- Use the address on the notice, not nationality or a later location, to choose 90 or 150 days.
- The petition type, court guidance and any equitable-tolling issue must be checked separately.
What should I check before filing?
These checks help you review the result. They do not activate a calendar date or certify that the deadline applies.
Common questions
Find answers about when this 90-day period starts, how it is counted, what can change it and how to keep your calculation.
Starting the clock
Does the clock start on the mailing of the notice of deficiency, or when I first learned of it?
The period runs from the mailing of the notice of deficiency as the rule defines it, not from the day you read about it, received a courtesy copy or attended a hearing. Use the date shown on the docket or in the service record.
Read 26 USC 6213Counting days and filing
Is it 90 calendar days or business days?
Calendar days. Count intermediate weekends and holidays. If the final day is a Saturday, Sunday or legal holiday, Tax Court Rule 25 carries it forward to the next day that is not one of those.
Tax Court Rule 25Which time zone and filing cutoff apply?
The Tax Court’s electronic filing system and its rules control the filing cutoff. This calculator does not verify system availability on a given day.
Tax Court Rule 25What if the court is inaccessible on the last day?
Tax Court Rule 25 and the statute address inaccessibility of the filing location. Check the court’s notices. This calculator does not predict an outage.
Tax Court Rule 25Extensions and local rules
Can the court extend this deadline?
The Tax Court cannot extend the statutory filing period. Culp v. Commissioner holds the period non-jurisdictional and equitably tollable in the Third Circuit; the Tax Court continues to treat it as jurisdictional outside that circuit. Never rely on tolling without forum-specific advice. A request does not itself extend the period, and no discretionary extension is calculated here.
Read 26 USC 6213Do local rules, standing orders or a scheduling order change the date?
They can. Many courts set their own periods by local rule, standing order or case-specific order, and those control over the national default. This calculator gives the national-rule date only; compare it with any order in the case before relying on it.
Choosing the right calculator
Does this calculator decide whether the rule applies to my case?
No. It calculates a period from the date you provide under the cited rule. It does not decide whether the rule governs your filing, whether an exception applies, or whether the filing has merit. Those questions need separate review.
Can I calculate the deadline without an account?
Yes. Enter the trigger date to see the free national-rule calculation, citation, counting steps and warnings. You can add court context after the result. Missing court review keeps the result provisional.
Results, records and your case
What is included in an Evidence Record?
The retained inputs, result, cited rule, calculation working, warnings and review state. The PDF includes a payload digest and retained-data appendix, and the record can be verified against its fingerprint later. It records the calculation, not a guarantee of legal correctness.
Does saving to a case activate the calendar?
Not automatically. Provisional records remain subject to review. A separately labeled manual date does not alter the original calculation.
Official sources and review
The period and the counting method come from different provisions. The official source is the court’s published rules; the reading links open the rule text at the Legal Information Institute.
| Provision | Purpose |
|---|---|
| 26 U.S.C. 6213(a); Tax Court Rule 25 | Trigger and period |
| Tax Court Rule 25 | Counting, legal holidays in the District of Columbia and the last day |
Rule record reviewed . Guide sources checked . Next source check .
Published by Deadline Engine. This tool calculates the ordinary period under the cited rule. It does not decide whether the rule applies, obtain an extension or file anything for you.