Can I add a priority claim to a patent after it has been issued?

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.

Yes, it is possible to add a priority claim to a patent after it has been issued, but the process requires filing a reissue application. The MPEP states:

‘A reissue application can be filed to correct the failure to adequately claim priority under 35 U.S.C. 119(a)-(d) or (f) or 35 U.S.C. 120 in the issued patent.’

To add a priority claim, you would need to:

• File a reissue application under 35 U.S.C. 251
• Amend the specification to include the required reference
• Ensure the reissue application is filed within the time period set forth in 35 U.S.C. 119(a)-(d) or (f)

It’s important to note that adding a priority claim may affect the patent’s term and could potentially impact its validity if prior art emerges between the new priority date and the original filing date.