If an applicant fails to respond to an Office Action, the application becomes abandoned as of the day after the due date for response to the Office Action, with the applicant being able to revive the application up until the extendable due date. See 37 CFR 1.135(a). Thus, if an Office Action issued March 1, 2013 with a period for response ending June 1, 2013, the application becomes abandoned June 2, 2013 even though the applicant can still save the application until September 1, 2013. Here’s how I got here.
First, according to the MPEP, the date of the abandonment is after midnight of the date the period for reply actually expired. This “date the period for reply actually expires” is normally the end of the 3-month shortened statutory period. See MPEP 711.04(a).
Second, the Patent Office form for unintentionally abandoning an application PTO/SB/64 also confirms this understanding.
The above-identified application became abandoned for failure to file a timely and proper reply to a notice or action by the
United States Patent and Trademark Office. The date of abandonment is the day after the expiration date of the period set
for reply in the office notice or action plus any extensions of time actually obtained.
Third, it makes logical sense that an application becomes abandoned after a period for reply.