What is the difference between preliminary amendments filed with the application and those filed after the filing date?

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 timing of a preliminary amendment significantly affects its status within a patent application. MPEP 608.04(b) clarifies this distinction:

A preliminary amendment present on the filing date of the application (e.g., filed along with the filing of the application) is considered a part of the original disclosure. […] A preliminary amendment filed after the filing date of the application is not part of the original disclosure of the application.

In essence, preliminary amendments submitted with the initial application filing are treated as part of the original disclosure. However, any preliminary amendments filed after the application’s filing date are not considered part of the original disclosure. This distinction is crucial for determining what constitutes new matter in the application and can affect the examination process.