When should subsequent applications for interim extension 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.

For subsequent applications for interim extension, the filing window is different from the first application. According to MPEP 2754.02:

“Each subsequent application for interim extension must be filed during the period beginning sixty days before and ending thirty days before the expiration of the preceding interim extension.”

This means that for any interim extension after the first one, applicants have a 30-day window to file, starting 60 days before the current interim extension expires and ending 30 days before its expiration.