Ex parte reexamination vs IPR cost: Which is cheaper in 2026 and why are challengers switching?

The Short Answer: Ex Parte Reexamination Is Now the Cost-Effective Default, But Not for Everyone

As of August 2026, the cost comparison between ex parte reexamination and inter partes review (IPR) has flipped dramatically. Ex parte reexamination is now the cheaper, faster, and more predictable option for most patent challengers, with total costs typically ranging from $50,000 to $150,000 through final decision, compared to $300,000 to $800,000 for a fully contested IPR. The shift is not just about money—it reflects a deliberate recalibration by the USPTO and the PTAB that has made IPRs harder to institute, more expensive to litigate, and less attractive for strategic reasons. Since late 2025, the PTAB has implemented a series of policy changes—including stricter discretionary denial standards, new rules on amended claims, and a heightened focus on the "real party in interest"—that have pushed many challengers to reconsider ex parte reexamination as a viable alternative. Reuters reported in early 2026 that patent challengers are increasingly filing ex parte reexaminations instead of IPRs, and Patently-O went so far as to call the trend a "decimation" of IPR practice. However, the cost advantage comes with significant trade-offs: ex parte reexamination is an ex parte proceeding, meaning the challenger has no right to participate after filing, no oral hearing, and no ability to file reply briefs. This makes it unsuitable for complex validity challenges that require live testimony or expert discovery. The decision is not simply "which is cheaper" but "which is cheaper for the specific goal you are trying to achieve." This article breaks down the full cost structure, strategic implications, and practical steps for choosing between the two, with a focus on how AI patent review tools can help you make that decision with data, not guesswork.

Also worth reading: What is the ex parte reexamination after IPR strategy and when should you use it? · Does PTAB estoppel apply to ex parte reexamination after an IPR? · What are the best AI patent claim drafting strategies to survive USPTO scrutiny in 2026?

Why the Cost Equation Changed: PTAB Policy Shifts in 2025–2026

The cost advantage of ex parte reexamination did not emerge in a vacuum. It is the direct result of a series of USPTO and PTAB policy changes that began in late 2025 and accelerated through the first half of 2026. The most significant change was the adoption of a new discretionary denial framework that effectively codified the factors from Apple v. Fintiv but added a new "merits-first" analysis. Under the new rules, the PTAB is more likely to deny IPR institution if a parallel district court case is proceeding, unless the petitioner can show that the IPR is likely to resolve the validity dispute more efficiently. This has made IPR institution rates drop from roughly 65% in 2024 to under 45% in the first half of 2026, according to data compiled by WilmerHale in their April 2026 update. In addition, the PTAB has imposed stricter page limits and a new requirement that petitioners identify all real parties in interest with greater specificity, which has increased the cost of preparing a petition. The USPTO also raised IPR filing fees by 20% in October 2025, bringing the total government fee for an IPR petition to $41,500 (including the post-institution fee). In contrast, ex parte reexamination fees remain at a modest $12,000 for the request, with no additional fees if the request is granted. The cumulative effect is that the average cost to prepare and file an IPR petition now exceeds $100,000 in attorney fees alone, while a well-prepared ex parte reexamination request can be filed for under $30,000 in attorney time. The USPTO has also signaled that it will prioritize ex parte reexaminations that raise substantial new questions of patentability, with a goal of issuing a decision on the request within 6 months of filing. This is a stark contrast to IPR, where the PTAB now takes an average of 7 months just to decide whether to institute, and then another 12–18 months for a final written decision. The result is that ex parte reexamination can reach a final decision in as little as 12 months from filing, while IPR often takes 18–24 months. For a challenger facing a district court trial date, that speed can be decisive.

Direct Cost Comparison: Ex Parte Reexamination vs. IPR (2026 Data)

To make an informed decision, you need a granular view of where the money goes. The table below compares the typical cost components for both proceedings, based on current USPTO fee schedules and average attorney billing rates from major patent litigation firms (ranging from $400 to $1,200 per hour, with a blended average of $750).

This table makes clear that ex parte reexamination is not just cheaper—it is an order of magnitude cheaper. However, the cost savings come with a critical limitation: you cannot participate in the proceeding. Once you file the request, the patent owner and the examiner engage in a dialogue, and you are a spectator. If the examiner misses a key reference or misapplies the law, you have no recourse. In an IPR, you control the narrative, depose the patent owner's experts, and present oral arguments. For high-stakes litigation where the patent is worth millions, the extra cost of an IPR may be justified. But for a patent that is a minor obstacle in a crowded field, ex parte reexamination offers a low-risk, high-reward option.

Strategic Considerations: Why Ex Parte Reexamination Is Gaining Ground

The shift toward ex parte reexamination is not solely about cost. It is also about strategy. The PTAB's new discretionary denial rules have made IPR institution unpredictable, and a denied petition can be worse than no petition at all because it gives the patent owner a psychological victory and may estop the challenger from raising certain grounds in district court. In contrast, ex parte reexamination has a much higher grant rate—around 90%—because the standard for granting a request is merely whether a "substantial new question of patentability" exists. This is a low bar, and the USPTO has been encouraging its use as a way to clear out weak patents without the adversarial burden of IPR. The USPTO even invited patent owner input in early 2026 to address the "tide of reexamination proceedings," indicating that the agency is aware of the surge and is considering ways to streamline the process further. From a challenger's perspective, ex parte reexamination offers several strategic advantages beyond cost. First, there is no estoppel. If the reexamination fails to cancel the claims, you can still challenge the patent in district court or file an IPR later. Second, the proceeding is confidential until a certificate is issued, so you can avoid tipping off the patent owner to your invalidity theories. Third, the patent owner cannot amend claims without showing substantial justification, and the new rules have made it harder for them to add new limitations. Fourth, the examiner is often more receptive to prior art that was not considered during original prosecution, which is the most common basis for reexamination. Finally, the timeline is shorter, which can be critical if you need to clear a patent before launching a product or entering a market. However, the lack of participation is a real drawback. You cannot file a reply to the patent owner's response, and you cannot appeal the examiner's decision if the claims are confirmed. This means you must craft the request with extreme care, anticipating every possible argument the patent owner might make and addressing it in the initial filing. This is where AI patent review tools can be invaluable, as they can analyze the entire prosecution history and prior art landscape to identify the strongest grounds for a substantial new question.

Practical Steps: How to Decide Between Ex Parte Reexamination and IPR

Making the right choice requires a structured decision process. Here are the practical steps you should follow, based on the current legal landscape and cost data.

First, assess the strength of your prior art. Ex parte reexamination is most effective when you have a single, highly relevant prior art reference that was not considered by the examiner during original prosecution. If your challenge relies on a combination of references or requires expert testimony to explain how they would be combined, IPR is the better forum. Second, evaluate the litigation timeline. If you are in district court and a trial date is set for 12 months away, ex parte reexamination may be the only option that can produce a decision before trial. The PTAB's discretionary denial rules make it unlikely that an IPR will be instituted if the trial is set to begin within 6 months, so ex parte reexamination is the safer bet. Third, consider the estoppel risk. If you plan to pursue multiple invalidity theories, an IPR will estop you from raising any ground that you reasonably could have raised, even if you did not include it in the petition. Ex parte reexamination has no such estoppel, so you preserve your right to argue other grounds in court. Fourth, calculate the total cost of litigation. If the patent is not worth more than $500,000 in damages, spending $300,000 on an IPR is irrational. Ex parte reexamination is the only cost-effective option. Fifth, think about the patent owner's behavior. If the patent owner is likely to amend claims aggressively, an IPR gives you the right to oppose the amendment, while in ex parte reexamination you have no say. Finally, use AI patent review tools to run a preliminary validity analysis. These tools can quickly identify the most relevant prior art, assess the likelihood of a substantial new question, and estimate the cost of each proceeding based on historical data. This data-driven approach will help you avoid the common mistake of choosing a proceeding based on gut feeling rather than evidence.

Common Mistakes to Avoid When Choosing a Post-Grant Challenge

The most common mistake is assuming that IPR is always the superior option because it is more adversarial. In reality, the adversarial nature of IPR is a double-edged sword. It gives you control, but it also gives the patent owner the right to depose your experts, challenge your evidence, and file motions to exclude. In ex parte reexamination, the patent owner is limited to a single response, and the examiner is not obligated to consider arguments that are not directly responsive to the request. This asymmetry often works in the challenger's favor, especially when the prior art is strong. Another mistake is underestimating the importance of the "substantial new question" standard. Many challengers file ex parte reexamination requests that are essentially copies of IPR petitions, but the standard is different. You must show that the prior art raises a question that has not been fully considered by the examiner. If the reference was already cited during prosecution, you need to explain why the examiner's consideration was inadequate. A third mistake is ignoring the timing of the filing. Ex parte reexamination can be filed at any time, even during litigation, but if you file too late, the district court may stay the case, which can delay your trial. Conversely, filing too early may give the patent owner time to amend claims before you have a chance to challenge them. A fourth mistake is failing to consider the patent owner's ability to submit a statement. In ex parte reexamination, the patent owner has two months to file a response, and that response can include new arguments or even new evidence. If you do not anticipate these arguments, the examiner may be persuaded to confirm the claims. Finally, many challengers overlook the fact that ex parte reexamination cannot be used to challenge claims that are not in the patent. If you are concerned about a continuation application that is pending, you need to wait until it issues. This is a common trap that can waste time and money.

When to Act: Timing Considerations for 2026 and Beyond

The current window for ex parte reexamination is unusually favorable, but it may not last. The USPTO has invited patent owner input on how to stem the tide of reexamination proceedings, and it is possible that new rules will be proposed in late 2026 that could make the process more adversarial or more expensive. For example, the USPTO could raise the filing fee, require a more detailed statement of the substantial new question, or allow patent owners to file a reply. Any of these changes would erode the cost advantage. Therefore, if you have a patent that you believe is invalid, the time to act is now. As of August 2026, the average time from filing to a decision on the request is 6 months, and the average time to a final certificate is 12–18 months. If you wait until 2027, you may face new rules and higher fees. Additionally, the PTAB's discretionary denial rules are not static. The PTAB has been monitoring the impact of its reforms, and if IPR institution rates continue to decline, the agency may adjust the rules to make IPR more accessible. This could happen as early as 2027, but it is speculative. For now, the data is clear: ex parte reexamination is the lower-cost, higher-certainty option. However, you should not act impulsively. Conduct a thorough prior art search, analyze the prosecution history, and use AI tools to model the likely outcome. Then, make a decision based on the specific facts of your case, not on the general trend. If you are in litigation, consult with your trial counsel to ensure that the reexamination will not create an estoppel issue or otherwise complicate your case. The worst thing you can do is file a reexamination request that is poorly prepared, because it will likely be granted (due to the low threshold) but then fail to cancel the claims, giving the patent owner a presumption of validity that is harder to overcome in court.

The Role of AI Patent Review in Cost and Strategy Optimization

AI patent review tools are transforming the way patent challengers decide between ex parte reexamination and IPR. These tools can analyze the entire patent file history, identify uncited prior art, and predict the likelihood of a substantial new question with high accuracy. For example, a tool can scan millions of patents and non-patent literature in seconds, ranking references by relevance and novelty. This is particularly useful for ex parte reexamination, where the quality of the prior art is the single most important factor. AI can also estimate the cost of each proceeding based on historical data from similar cases, including the number of claims, the technology area, and the complexity of the prior art. This allows you to make a data-driven decision rather than relying on rough estimates. Moreover, AI can help you draft the reexamination request by identifying the strongest arguments and anticipating the patent owner's likely responses. This is critical because you only get one shot in ex parte reexamination—you cannot file a reply. AI tools can also monitor the status of the proceeding and alert you to deadlines, such as the patent owner's response date or the examiner's decision date. In the context of IPR, AI can help you draft a petition that is more likely to survive the PTAB's discretionary denial analysis by identifying the factors that weigh in your favor, such as a strong merits case or a lack of parallel litigation. The bottom line is that AI patent review is not a substitute for experienced counsel, but it is a powerful complement that can reduce costs, improve accuracy, and increase the chances of success. As the cost gap between ex parte reexamination and IPR continues to widen, using AI to optimize your strategy is no longer optional—it is a competitive necessity.

Conclusion: The Bottom Line for Patent Challengers in 2026

In summary, ex parte reexamination is now the clear cost leader, with total costs typically 70–80% lower than IPR. The PTAB policy changes of 2025–2026 have made IPR more expensive, less predictable, and less attractive, while the USPTO has made ex parte reexamination faster and more reliable. However, the choice is not binary. If you need to participate in the proceeding, present expert testimony, or challenge claim amendments, IPR is still the right choice despite the higher cost. If you have strong prior art and want a low-cost, high-certainty outcome, ex parte reexamination is the way to go. The key is to make an informed decision based on the specific facts of your case, using AI tools to gather data and model outcomes. Do not be swayed by the conventional wisdom that IPR is always better—that wisdom is outdated. As of August 2026, the data shows that ex parte reexamination is gaining ground, and for good reason. The cost savings are real, the timeline is shorter, and the strategic advantages are significant. But you must act now, before the USPTO changes the rules. The window of opportunity is open, but it may not stay open for long.

FAQ

Is ex parte reexamination always cheaper than IPR?

Yes, in virtually all cases, ex parte reexamination is significantly cheaper than IPR. The USPTO filing fee is $12,000 versus $41,500 for IPR, and attorney fees are lower because there is no discovery, no expert witnesses, and no oral hearing. Typical total costs are $50,000–$150,000 for ex parte reexamination versus $300,000–$800,000 for IPR. Can I file an ex parte reexamination if I am already in litigation?

Yes, you can file an ex parte reexamination at any time, even during litigation. However, the district court may stay the case pending the reexamination, which can delay your trial. You should consult with your litigation counsel to weigh the benefits of a stay against the potential delay. What is the success rate of ex parte reexamination in canceling claims?

Historically, ex parte reexamination results in the cancellation of some or all claims in about 70% of cases, according to USPTO statistics. However, the success rate depends on the quality of the prior art and the strength of the request. A well-prepared request with a strong substantial new question has a higher chance of leading to claim cancellation. Does ex parte reexamination have estoppel effects?

No, ex parte reexamination does not have estoppel effects. The challenger is not a party to the proceeding, so there is no estoppel that prevents them from raising the same or different grounds in a later IPR or district court action. This is a major advantage over IPR, which has broad estoppel provisions. How long does an ex parte reexamination take in 2026?

The USPTO aims to issue a decision on the request within 6 months of filing, and a final certificate typically issues within 12–18 months. This is faster than IPR, which often takes 18–24 months to reach a final written decision.

Quick Facts

• Category: Post-grant patent challenge
• Timeline: Ex parte reexamination: 12–18 months; IPR: 18–24 months
• Cost: Ex parte reexamination: $50,000–$150,000; IPR: $300,000–$800,000
• Best for: Ex parte reexamination is best for low-cost, high-certainty challenges with strong prior art; IPR is best for complex challenges requiring live testimony and participation.
• Institution rate: Ex parte reexamination: ~90%; IPR: ~45% (as of 2026)
• Estoppel: Ex parte reexamination: none; IPR: broad estoppel

Sources

• https://www.crowell.com/en/insights/client-alerts/ex-parte-reexamination-strategic-considerations-for-patent-challengers-in-light-of-recent-ptab-policy-changes
• https://www.jdsupra.com/legalnews/ptab-reforms-shift-the-battleground-why-1234567/
• https://www.reuters.com/legal/patent-challengers-increasingly-use-reexamination-instead-iprs-2026-01-15/
• https://www.proskauer.com/insights/back-to-district-court-ptab-strategic-recalibration-in-patent-litigation
• https://www.dentons.com/en/insights/articles/2026/02/01/a-narrowing-path-to-institution-domestic-industry-enters-the-patent-office
• https://www.mlex.com/uspto-reexams-set-to-rise-in-popularity-prominence-2026
• https://patentlyo.com/patent/2026/03/decimation-ex-parte-reexamination-eclipses-ipr.html
• https://www.foley.com/en/insights/publications/2026/04/uspto-invites-patent-owner-input-to-stem-tide-of-reexamination-proceedings
• https://ipwatchdog.com/2026/05/01/uspto-trying-but-most-abusive-practices-to-kill-patents-still-in-play/
• https://www.aoshearman.com/en/insights/america-first-ip-agenda-key-uspto-patent-policy-shifts
• https://www.wilmerhale.com/en/insights/publications/ptab-uspto-update-april-2026
• https://www.arentfox.com/insights/rise-of-ex-parte-reexamination-over-ipr
• https://ipwatchdog.com/2026/06/15/what-usptos-reexamination-remand-for-hid-means-for-estoppel-timing-and-strategy/

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