Some time after a patent application has been filed, the Patent and Trademark Office will communicate with the applicant. Most communications require a response from the applicant within a certain time frame. While the default period for most responses is six months, a shorter time is usually set. For example, responses to rejections are usually due three months from the mailing date of the rejection.

When a shortened due date cannot be met, extensions of time may be purchased, but they escalate (up to $500 per month) and may hasten the expiration date of the resulting patent. Therefore, it is important to respond to office actions promptly. Patent law firms have sophisticated docketing systems to track due dates for responses, maintenance fees and annuities.