What are the consequences of adding new matter to 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.

Adding new matter to a patent application can have serious consequences:

• Rejection or objection: The USPTO will issue a rejection or objection to the new matter. As stated in MPEP 608.04, ‘If new matter is added to the claims, the examiner should reject the claims under 35 U.S.C. 112(a) or pre-AIA 35 U.S.C. 112, first paragraph – written description requirement.’
• Loss of priority date: New matter may result in a later effective filing date for the affected claims.
• Inability to claim benefit: As per the MPEP, ‘New matter includes not only the addition of wholly unsupported subject matter, but may also include adding specific percentages or compounds after a broader original disclosure, or even the omission of a step from a method.’
• Need for continuation-in-part: To properly include the new matter, a continuation-in-part application may be necessary.

It’s crucial to ensure all subject matter is fully supported by the original disclosure to avoid these issues.