Brief Notes

371 vs. 111(a) Entry into the US


This brief note is not legal advice and is for educational purposes only.
This area is very complicated and you really should contact your attorney as this brief note just scratches the surface on this area and important property rights can be lost by picking the wrong entry method. Verbum sap.
There are two main ways to enter the US national stage for a non-provisional application:


The most common way to enter the US is from a PCT (Patent Cooperation Treaty) or International Application. Entry into the US from a PCT/international application must occur within 30 months from the priority date (see

Here is a chart denoting some major differences between the entry methods.

PCT = PCT/international

Issue 371 entry 111(a) entry
Application Claims and spec based on PCT Claims and spec based on what is filed (amendments during PCT don't count)
Claims Based on PCT - no new matter CIP (continuation-in-part) allowed
Examination No accelerated exam, PCT-PPH available (PPH = Patent Prosecution Highway) Can have accelerated exam, PCT-PPH available
Filing Date PCT filing date Date filed in US - however for prior art purposes filing date = PCT filing date

The difference in filing date is an important one to consider as it can have a major effect on patent term length and the examination process. Additional complications can arise if your application spans the pre-AIA to AIA (America Invents Act) transition period in which case election of how the claims are examined may be needed.

Note that we have NOT discussed the documentation required to establish entry under either method or the timing or timetable of events or fees. Consult your attorney.


Welcome to the entry choices. Discuss with your attorney BEFORE entry which approach they recommend and ask specifically why as it can make a big difference.

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