What are A, B, and C delays?

A-delays are missed USPTO response deadlines (e.g., a first office action later than 14 months from filing). B-delay is issuance later than three years from filing. C-delays cover interferences, secrecy orders, and successful appeals. Together they extend the patent term.

Why is overlap subtracted?

Under 35 U.S.C. 154(b)(2)(A), periods of A, B, and C delay that overlap in time are counted only once. If the same calendar days qualify as both an A-delay and a B-delay, you cannot add them twice, so overlap days are deducted from the gross total.

What is applicant delay?

Applicant delay is time the applicant failed to engage in reasonable efforts to conclude prosecution — for example, taking more than three months to reply to an office action. Those excess days are subtracted from the PTA under 154(b)(2)(C).

Is this the official USPTO number?

No. The USPTO computes PTA with detailed rules, including specific deadline calculations and reductions. This tool is a verification aid using the day counts you supply; always reconcile against the official PTA on the issued patent and petition any error within two months.

What are the statutory deadlines for A-delay?

The common A-delay deadlines are 14 months from filing to the first office action, 4 months to respond to a reply or appeal, 4 months to act after a Board decision, and 4 months from the issue fee payment to issuance. Days late on each are A-delay days.

Patent Term Adjustment (PTA) Calculator

Patent term adjustment restores time lost to USPTO processing delays, extending a patent’s term beyond the standard 20 years from filing. This calculator sums the three statutory delay categories under 35 U.S.C. 154(b), removes overlap, and subtracts applicant delay to estimate the net PTA days you should expect.

How it works

The net adjustment combines the three delay buckets and then applies the two mandatory reductions:

gross PTA = A delay + B delay + C delay
net PTA   = gross PTA − overlap days − applicant delay days

A-delays come from the USPTO missing its 14/4/4/4-month milestones, B-delay from issuance later than three years after filing, and C-delays from interferences, secrecy orders, and successful appeals. Overlap is removed because the statute counts simultaneous delay only once, and applicant delay is subtracted because the patentee cannot claim time it caused.

Example and tips

If the USPTO accrues 120 A-delay days and 200 B-delay days, with 90 days of overlap and 30 days of applicant delay, the net PTA is 120 + 200 − 90 − 30 = 200 days. Always reconcile your figure against the PTA printed on the issued patent: the USPTO frequently miscounts overlap and applicant delay, and you have a limited window — typically two months from issuance — to petition for a correction.