What are the two types of signatures accepted for patent correspondence?

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 USPTO accepts two types of signatures for patent correspondence:

• Handwritten signature: An original signature personally signed in permanent dark ink or its equivalent.
• S-signature: A signature inserted between forward slash marks, which can include electronic or mechanical signatures.

As stated in 37 CFR 1.4(d): “Correspondence filed in the Office, which requires a person’s signature, may be filed with one of two types of signatures: (A) handwritten signature; and (B) ‘S-signature.’”