When should a Demand for International Preliminary Examination be filed?

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.

According to MPEP 1865, the Demand must be filed prior to the expiration of whichever of the following periods expires later:

• (A) three months from the date of transmittal to the applicant of the international search report and the written opinion; or
• (B) 22 months from the priority date.

The MPEP also notes: “In order to take advantage of a national phase entry time limit of at least 30 months from the priority date in relation to all States designated in the international application, it may be necessary to file a demand before the expiration of 19 months from the priority date.”