How to Verify and Challenge USPTO PTA Calculations

The USPTO calculates patent term adjustment (PTA) using an automated algorithm, and the result is printed on the face of every issued patent. But the USPTO's calculation is not always correct. Programming errors, failure to account for safe harbor statements, and misapplication of applicant delay rules have all resulted in incorrect PTA determinations — sometimes costing patentees months or years of patent term. Patentees have a limited window to challenge an incorrect PTA, and missing the deadline means living with the USPTO's number. This guide explains how to read and verify the USPTO's PTA calculation, when and how to request reconsideration, and what to do if the USPTO's decision is unfavorable.

Scope: This article covers the procedures for verifying and challenging PTA under 35 U.S.C. § 154(b)(3)-(4) and 37 CFR 1.705. For an explanation of what PTA is and how it is calculated, see our PTA vs PTE comparison. For details on applicant delay, see our applicant delay guide.

Where to Find the USPTO's PTA Calculation

The PTA is stated on the front page of every US utility patent, typically in a notice reading something like: "Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by X days."

For a more detailed breakdown, the USPTO's Patent Center (patentcenter.uspto.gov) provides the PTA calculation details, including the individual A, B, and C delay components, overlap, and applicant delay reductions. This is the starting point for any verification.

Common Reasons the USPTO Gets PTA Wrong

Several patterns account for the majority of PTA errors:

Safe Harbor Statements Not Recognized

The most well-documented issue. When an applicant files an IDS with a safe harbor statement under 37 CFR 1.704(d), the IDS should not generate applicant delay. However, the USPTO's automated algorithm has historically failed to account for safe harbor statements, improperly reducing PTA. This problem persists even after the USPTO required Form PTO/SB/133 and document code "PTA.IDS" starting in July 2023. The USPTO acknowledged this issue and implemented an interim recalculation procedure using Form PTO/SB/134.

Software Bugs

In September 2024, the USPTO announced that a programming error in a recent software update caused its PTA algorithm to miscalculate A-Delay and overlap for some patents issued between March 19, 2024 and July 30, 2024. The USPTO estimated that approximately 1% of patents during this period received an incorrect PTA. For many others, the inaccurate A-Delay was offset by an equally inaccurate overlap calculation, producing a correct total by coincidence.

The USPTO did not correct affected patents on its own. Instead, patentees had to file a timely request for reconsideration under 37 CFR 1.705(b). The USPTO waived the request fee and extension fee for patents affected solely by this coding error.

Misapplication of Applicant Delay Rules

The automated algorithm applies the rules of 37 CFR 1.704 mechanically. It may not properly account for situations where, under Supernus v. Iancu, 913 F.3d 1351 (Fed. Cir. 2019), a PTA reduction exceeds the actual period of applicant inaction. See our applicant delay guide for details on the Supernus holding and its implications.

USPTO Closings Not Reflected

When the USPTO is closed due to weather or emergency, the closure extends the 3-month applicant response deadline under ArQule v. Kappos, 793 F.Supp.2d 214 (D.D.C. 2011). The automated algorithm may not always account for these closings, resulting in overstated applicant delay.

Incorrect Overlap Calculation

The overlap between A-Delay and B-Delay must be subtracted to avoid double counting. The algorithm's overlap calculation has been a source of errors, as demonstrated by the 2024 software bug.

How to Verify PTA Independently

A thorough PTA verification requires reconstructing the calculation from the prosecution history:

Step 1: Identify the key dates. Gather the filing date (or national stage commencement date), the mailing date of each Office action and notice, the filing date of each applicant response, and the grant date.

Step 2: Calculate A-Delay. Check whether the USPTO met each of the 14/4/4/4 deadlines under 35 U.S.C. § 154(b)(1)(A). For each missed deadline, count the days of delay.

Step 3: Calculate B-Delay. Determine whether the patent issued within 3 years of the actual filing date, excluding RCE periods and other statutory exclusions under § 154(b)(1)(B).

Step 4: Calculate C-Delay. Check for interference/derivation proceedings, secrecy orders, or successful appellate review under § 154(b)(1)(C).

Step 5: Calculate overlap. Identify any periods that generate both A-Delay and B-Delay simultaneously, and subtract the overlap.

Step 6: Calculate applicant delay. Review each applicant response for timeliness under 37 CFR 1.704(b), and check for any § 1.704(c) triggering events (supplemental replies, post-allowance filings, abandonment, etc.). Verify safe harbor statements.

Step 7: Compare. Net PTA = A + B + C − overlap − applicant delay. Compare your result with the USPTO's.

Our Patent Expiration Calculator automates much of this process and can flag discrepancies worth investigating further.

Requesting Reconsideration Under 37 CFR 1.705(b)

If you believe the USPTO's PTA calculation is incorrect, the primary remedy is a request for reconsideration under 37 CFR 1.705(b).

Deadline

The request must be filed within 2 months of the patent grant date. This deadline can be extended by up to 5 additional months under 37 CFR 1.136(a), for a maximum window of 7 months from grant. The extension requires payment of an extension fee.

Requirements

The request must include:

1. The fee set forth in 37 CFR 1.18(e) (unless the fee is waived, as in the 2024 software error situation).
2. A statement of the facts involved, including the correct PTA calculation and the basis for the disagreement.
3. Any relevant information not recorded in the USPTO's PALM system, such as the circumstances surrounding an IDS filing for a Supernus-type argument.

What Happens Next

The Office of Petitions will manually review the PTA calculation. If the USPTO agrees with the patentee's calculation, it will issue a certificate of correction adjusting the PTA. If the USPTO disagrees, it will issue a decision under 35 U.S.C. § 154(b)(3)(B)(ii). The patentee will typically have one opportunity to respond to the USPTO's recalculation within two months.

Safe Harbor Recalculation Procedure

For PTA errors specifically caused by unrecognized safe harbor statements, the USPTO's interim procedure allows a simplified request using Form PTO/SB/134. When the USPTO receives this form, the Office of Petitions will manually review the full PTA calculation under 37 CFR 1.702 through 1.704 — not just the safe harbor issue. If the patentee does not respond to the recalculation, the USPTO will issue a certificate of correction if warranted.

Civil Action Under 35 U.S.C. § 154(b)(4)

If the USPTO's decision on a 37 CFR 1.705(b) request is unfavorable, the patentee may seek judicial review by filing a civil action under 35 U.S.C. § 154(b)(4)(A) within 180 days of the Director's decision. These cases are typically filed in the US District Court for the Eastern District of Virginia.

Several important PTA decisions have come through this path, including the Supernus, Intra-Cellular, and Lundbeck cases discussed in our applicant delay guide.

Worked Example: Correcting a Safe Harbor Error

Common Mistakes

• Missing the 2-month deadline. The 1.705(b) request deadline runs from the grant date, not from when you discover the error. Build PTA verification into your post-grant workflow.
• Assuming the USPTO's number is correct. The automated algorithm has documented error patterns. Every patent with an IDS filed after a reply or after allowance should be checked for safe harbor statement recognition.
• Not preserving the record. A Supernus-type challenge requires evidence of when the applicant first learned of the prior art cited in the IDS. Maintain records of foreign office action dates and citation notifications.
• Filing the wrong form. For safe harbor corrections, use Form PTO/SB/134 under the interim procedure. For all other PTA disputes, file a formal request under 37 CFR 1.705(b) with the required fee and factual statement.
• Overlooking the 2020 rule changes. Patents issuing from applications where a notice of allowance was mailed on or after July 16, 2020 are subject to the revised 37 CFR 1.704(c) rules. Earlier patents may also benefit if a timely 1.705(b) request is filed.

Last reviewed: April 2026

Authorship: Written by the patentreply.ai editorial team. See our editorial methodology for how guides are drafted, sourced, and reviewed.

Legal disclaimer: This article is for informational purposes only and does not constitute legal advice. Consult a registered patent attorney or agent for advice specific to your situation. patentreply.ai is not a law firm.