What is the effective filing date for claims in a continuation-in-part 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 effective filing date for claims in a continuation-in-part (CIP) application depends on whether the claims are supported by the parent application:

“If the application is a continuation-in-part of an earlier U.S. application or international application, any claims in the new application not supported by the specification and claims of the parent application have an effective filing date equal to the actual filing date of the new application. Any claims which are fully supported under 35 U.S.C. 112 by the earlier parent application have the effective filing date of that earlier parent application.” (MPEP 2139.01)

In other words:

• Claims supported by the parent application: Effective filing date is the filing date of the parent application
• New claims not supported by the parent application: Effective filing date is the actual filing date of the CIP application