What is the difference between a 35 U.S.C. 111(a) application and a 35 U.S.C. 371 national stage application?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The key difference lies in the filing process and requirements:

• 35 U.S.C. 111(a) application: A direct U.S. patent application.
• 35 U.S.C. 371 national stage application: Enters the U.S. national stage from an international PCT application.

The MPEP states: “If the initial submission does not include any indication that the submission is made under 35 U.S.C. 371, the application will be treated as an application filed under 35 U.S.C. 111(a).” This highlights the importance of proper identification during filing.