An inter partes review timeline typically runs 18 to 24 months from the day the petition is filed to the day the Patent Trial and Appeal Board issues its final written decision. The schedule breaks into two roughly equal halves: about six months from filing to the institution decision, then a statutory 12 months from institution to the final decision. Because nearly every deadline is fixed by statute or regulation, the process is far more predictable than district court patent litigation.
One deadline sits outside that timeline and controls whether it ever begins.
The One-Year Bar Before You Can File
A petition cannot be filed more than one year after the petitioner, its real party in interest, or a privy was served with a complaint alleging infringement of the patent. Miss that window and the PTAB will reject the petition outright, no matter how strong the invalidity arguments are. The only exception is a request for joinder with an already-instituted proceeding.
The clock starts on the date the infringement complaint is served, not the date the case is filed or the date the party first learns of the patent. Planning for IPR should begin the moment a complaint arrives.
From Petition to Institution: Roughly Six Months
The proceeding begins when the petitioner files a petition identifying the challenged claims and presenting prior art evidence of anticipation or obviousness. The petition is capped at 14,000 words, excluding tables of contents, tables of authorities, mandatory notices, and exhibits. After procedural review, the PTAB issues a Notice of Filing Date Accorded, typically within 14 days of filing.
The patent owner then has three months from the notice date to file an optional preliminary response, also capped at 14,000 words, arguing why the Board should decline to institute. The preliminary response may include supporting evidence and expert declarations, but it cannot include a motion to amend the challenged claims.
The PTAB must issue its institution decision within three months of receiving the preliminary response, or within three months after the deadline for that response passes if none is filed. When the patent owner uses its full three months, the institution decision lands about six months after the Notice of Filing Date Accorded. The Board institutes when the petitioner shows a reasonable likelihood of prevailing on at least one challenged claim, a threshold deliberately lower than the preponderance standard used at trial.
Discretionary Denial Can End Things Here
Even a petition that clears the reasonable-likelihood bar can be denied on discretionary grounds. The PTAB’s precedential decision in Apple v. Fintiv weighs factors including whether a parallel district court case has a trial date close to the projected PTAB deadline, the investment courts and parties have already made in parallel proceedings, and the overlap between the petition’s grounds and the parallel case. A March 2025 USPTO memorandum added considerations including the settled expectations of the parties and how long the challenged claims have been in force. The weight given to each factor has shifted with changes in USPTO leadership and policy.
The 12-Month Trial Phase
Once trial is instituted, the PTAB issues a scheduling order, and the entire post-institution phase must end with a final written decision within 12 months. That statutory ceiling drives the pace of everything that follows.
Briefing Sequence
The patent owner has three months from institution to file its full response to the petition. This response typically includes expert testimony and, if the patent owner wants to modify its claims, an original motion to amend. The patent owner gets one shot at that motion and must confer with the Board before filing. Proposed substitute claims must be narrower than or equal in scope to the claims they replace.
The petitioner then has three months to file a reply and an opposition to any motion to amend. After that, the patent owner may file a sur-reply responding to arguments the petitioner raised in reply. The scheduling order sets specific due dates for each filing, and extensions are rare given the statutory deadline.
Limited Discovery
Discovery in IPR is far more limited than in district court. Routine discovery is available as of right and primarily consists of cross-examination depositions of witnesses who submitted declarations or affidavits. Anything beyond that, such as document requests or interrogatories, requires a motion showing the additional discovery is in the interests of justice. The Board grants those motions sparingly, which is a large part of why IPR moves so much faster than parallel litigation.
Oral Hearing
The Board typically provides one hour of argument per side for a single IPR, though parties can request more or less time. The scheduling order sets the hearing date, and it usually falls near the end of the 12-month window.
Settlement Can Cut the Timeline Short
Parties can settle and terminate an IPR at any point before the Board decides the merits. A joint request from the petitioner and patent owner will terminate the proceeding as to that petitioner, and no estoppel attaches to a petitioner who exits through settlement. Any settlement agreement or related side deal must be in writing and filed with the PTAB before termination. The Board can treat these agreements as business confidential upon request.
If settlement removes the last remaining petitioner, the Board is not required to end the proceeding. It may terminate the review or continue to a final written decision on its own, so settling with every petitioner does not guarantee the case ends.
Final Written Decision
The PTAB must issue its final written decision within one year of institution. The statute allows the Director to extend that deadline by up to six months for good cause, an authority delegated in practice to the Chief Administrative Patent Judge. Extensions are uncommon and typically arise from joinder of additional parties or other unusual procedural complications. The decision addresses the patentability of every challenged claim and any new or amended claims proposed during trial.
After the decision issues, the USPTO publishes a certificate canceling claims found unpatentable, confirming claims found patentable, and incorporating any surviving amendments. That certificate does not issue until all appeal deadlines have expired or any appeal has concluded.
After the Decision: 30 Days, Then 63 Days
A party unhappy with the final written decision has two options before heading to court, and both share the same 30-day filing window. A request for rehearing by the Board must be filed within 30 days of the decision, must identify specific matters the Board misapprehended or overlooked, and must point to where those issues were previously raised. Alternatively, a party may request Director Review, which allows the USPTO Director to personally review the Board’s decision. The same 30-day deadline applies, and a party cannot file both a rehearing request and a Director Review request for the same decision.
Either party may appeal the final written decision to the United States Court of Appeals for the Federal Circuit. The notice of appeal must be filed with the USPTO Director within 63 days of the final decision, or within 63 days of the Board’s action on a timely rehearing request. Once docketed, the case follows a formal briefing schedule, and the full appeal typically takes 9 to 18 months from notice through a Federal Circuit decision. Complex cases or requests for en banc review can push that further. The Federal Circuit reviews legal conclusions without deference and factual findings for substantial evidence. If the court reverses and finds canceled claims patentable, the USPTO issues an updated certificate restoring them.
Estoppel Attaches at the Final Decision
Once the final written decision issues, the petitioner, its real party in interest, and any privy cannot challenge the same claims on any ground that was raised or reasonably could have been raised during the IPR. The bar runs in both directions: no further USPTO proceeding on those grounds, and no invalidity argument on those grounds in federal district court or before the International Trade Commission. The “reasonably could have raised” language reaches beyond the specific references in the petition to references a reasonably diligent search would have uncovered, which is why leaving strong prior art out of a petition can foreclose its use later.
One Note on Cost
The timeline is predictable; the price is not modest. The base petition fee for challenging up to 20 claims is $23,750, with each additional claim at $470. If trial is instituted, the petitioner owes a post-institution fee of $28,125 for up to 20 claims and $940 per additional claim. There is no small- or micro-entity discount. USPTO fees alone for a 20-claim challenge taken through a full trial total $51,875, before counsel, experts, or any other litigation expense.