# How to Calculate Patent Term Adjustment

I recently assisted a client in paying his issue fee—the last step in patent prosecution before a patent is granted. Along with the notice that the issue fee was due, the USPTO provided notice of its determination of patent term adjustment (“PTA”). Since the USPTO has been known to err on its PTA calculations, it may be good practice to at least review the application timeline and determine whether the PTA was correctly calculated. I thought that a blog post about PTA may be useful. So how is PTA computed?

First, a little discussion of the purpose of PTA: The default term of a typical patent is twenty years, counted from the filing date of the patent application. Congress realized that the patent prosecution process can be rather lengthy, which eats into the patent’s lifespan, and so provided PTA to increase the life of certain patents. PTA is intended to compensate for extra-lengthy patent prosecution—at least when the process is slowed by the USPTO (applicant delays not only do not increase the patent term, but may actually decrease its lifespan, as the section on PTA calculation will show).

### How to Calculate PTA

Patent Term Adjustment is calculated with the following steps:

1. Determine the number of days delay and categorize those delays under A, B, or C delays (see below)
2. Determine the number of overlapping days between the A, B, and C delay periods
3. Determine the number of days delay caused by the patent applicant
4. The PTA is 1. minus 2. minus 3.

When the USPTO sends a Notice of Allowability to the patent applicant, it will also send a Determination of Patent Term Adjustment, which provides notice of the number of days PTA the applicant will receive.  Assuming that the patentee pays the maintenance fees during the patent’s lifetime and there are no disclaimers to the patent term, the patent will expire after the passage of twenty years plus the PTA.

A Delays: Failure of the USPTO to respond to a patent filing (e.g., office action or notice of allowance) within 14 months of filing
B Delays: Failure of the USPTO to issue the patent within three years of filing
C Delays: Delay due to interferences, secrecy orders, or successful appeals
Patent Applicant Delay: Delay caused by “applicant’s failure to engage in reasonable efforts to conclude prosecution of the application for the cumulative period in excess of three months” or “applicant’s failure to engage in reasonable efforts to conclude prosecution of the application.” This type of delay could be due to several actions by the applicant, including petitioning for deadline extensions and filing formal drawings too late.