How does an amendment affect the classification of a patent 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.

An amendment to a patent application can potentially affect its classification, particularly if it introduces new subject matter or significantly alters the scope of the claims. The MPEP 909.01(c) indicates that certain amendments may trigger a C* classification challenge: “Upon the receipt of an amendment which makes a C* classification challenge necessary, steps should be taken promptly in accordance with the C* classification challenge outlined in MPEP § 909.01(d).” However, it’s important to note that after the first action on the merits, changes to the classification are generally not made, as stated: “Generally, after a first action on the merits has been mailed C* classification will not be removed from an application’s classification picture.” This suggests that while amendments can potentially affect classification, there are limitations on when such changes are implemented.