What are the S-signature requirements for patent applications?

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.

S-signatures, or electronic signatures, must meet specific requirements for patent applications:

• Inserted between forward slash marks (//).
• Include the signer’s name.
• Be reasonably specific to identify the signer.
• Be handwritten or a facsimile of a handwritten signature.

According to MPEP 402.03: ‘The signature must consist only of letters, or Arabic numerals, or both. The S-signature must be signed in permanent dark ink or its equivalent.’