Most Tax Court cases begin with a deadline that the Court cannot extend: the time to file a petition after the IRS mails a notice of deficiency. More deadlines follow once a case is under way. This article summarizes how the 90-day period is counted, what counts as timely filing, and the other dates that matter in a Tax Court case.
The 90-Day Rule
Section 6213(a) of the Internal Revenue Code allows a taxpayer to petition the Tax Court within 90 days after a notice of deficiency (sometimes called a statutory notice) is mailed. The period is 150 days if the notice is addressed to a person outside the United States. The period runs from the mailing date, not the date the notice is received.
Two rules can affect the last day:
Weekends and holidays. Under section 6213(a), a Saturday, Sunday, or legal holiday in the District of Columbia is not counted as the last day. If the 90th day falls on one of those days, the petition is timely if filed on the next business day.
The date stated in the notice. The IRS normally lists the last day to file a petition on the notice of deficiency. Section 6213(a) treats a petition filed on or before that date as timely.
For example, if a notice of deficiency is mailed on Monday, March 2, 2026, the 90th day is Sunday, May 31, 2026. Because that day is a Sunday, a petition filed on Monday, June 1, 2026, would be timely. In practice, filing well before the last day avoids problems with mail, technology, or missing documents.
By law, the Tax Court cannot extend the time for filing a petition.
What Counts as Filing on Time
Electronic filing. Petitions can be filed through DAWSON, the Court’s electronic filing system. In most cases the Court must receive an electronically filed petition by 11:59 p.m. Eastern time on the last day to file.
The Court’s electronic filing system logs documents using Eastern time. For a filer in California, 11:59 p.m. Eastern time is 8:59 p.m. Pacific time.
Mail. Under the timely-mailing rule of section 7502, a petition that arrives after the deadline is generally treated as timely if it bears a legible U.S. Postal Service postmark dated within the filing period and was properly addressed with postage prepaid. Certified or registered mail, or a private delivery service designated by the IRS, provides stronger evidence of the mailing date. The Court cautions that a private postage-meter stamp does not prove timely mailing.
Hand delivery. Paper petitions may be delivered to the Court in Washington, D.C., between 8 a.m. and 4:30 p.m. Eastern time. The Court does not accept filings by fax or email.
If the Deadline Is Missed
A petition filed after the deadline is generally dismissed. The IRS may then assess the tax and begin collection. The usual remaining path is to pay the tax, file a claim for refund, and, if the IRS denies the claim or does not act on it within six months, file a refund suit in federal district court or the U.S. Court of Federal Claims.
Refund claims have their own deadlines. Under section 6511(a), a claim generally must be filed within three years from the time the return was filed or two years from the time the tax was paid, whichever is later. Under section 6532(a)(1), a refund suit generally must be filed within two years after the IRS mails a notice disallowing the claim.
A later collection due process hearing generally does not provide a second chance to dispute the underlying tax if the taxpayer received the notice of deficiency, because section 6330(c)(2)(B) limits those challenges.
Deadlines for Other Types of Petitions
Collection due process. A petition seeking review of an IRS collection due process determination is due within 30 days of the determination under section 6330(d)(1). In Boechler, P.C. v. Commissioner (2022), the U.S. Supreme Court held that this 30-day deadline is not jurisdictional and can be subject to equitable tolling, but that does not make a late filing advisable.
Innocent spouse relief. A taxpayer who requested relief from joint liability may petition the Tax Court after the IRS mails a final determination, or after six months if no determination has been issued. The petition must be filed no later than the 90th day after the final determination is mailed (section 6015(e)).
Other notices. The Tax Court also hears cases involving interest abatement, worker classification, passport certification, and whistleblower determinations, among others. Each has its own filing period, and the IRS notice generally states it.
Deadlines Once the Case Is Under Way
Answer and reply. The IRS generally has 60 days from service of the petition to file an answer (Rule 36). If a reply is needed, the petitioner has 45 days from service of the answer (Rule 37).
Discovery. Formal discovery generally may not begin until 30 days after joinder of issue, and it must be completed, with any motion to compel filed, no later than 45 days before the date set for calling the case from a trial calendar (Rule 70).
Stipulations and experts. A motion to compel a stipulation must be filed no later than 45 days before the calendar call (Rule 91). Expert witness reports must be served no later than 30 days before the call of the trial calendar (Rule 143(g)).
Trial preparation. The Court generally sends the notice setting a case for trial about five months before the trial date, together with a standing pretrial order that sets further deadlines, including the pretrial memorandum required in regular cases. A motion to proceed remotely may be filed up to 31 days before the first day of the trial session.
After trial. When the judge orders simultaneous briefs, opening briefs are due within 75 days after the trial concludes and answering briefs 45 days after that, unless the judge sets a different schedule (Rule 151). A motion for reconsideration of an opinion must be filed within 30 days after the opinion is served (Rule 161), and a motion to vacate or revise a decision within 30 days after the decision is entered (Rule 162).
Appeal. In a regular case, a notice of appeal must be filed with the Tax Court within 90 days after the decision is entered, or within 120 days if the IRS appeals first. Small tax case decisions cannot be appealed.
Practical Steps
Note the mailing date and the last filing date shown on the notice as soon as it arrives. Keep the envelope. Decide early whether to file electronically or on paper, and keep proof of the filing date. Once a case is docketed, calendar each deadline in the Court’s orders, since many are tied to the trial calendar rather than to the filing date.
Facing a Tax Court deadline?
Tax attorney Cassra Minai, Esq. can review your notice and the deadlines that apply in a confidential consultation.