patent maintenance fees

All utility patents which issue from applications filed on and after December 12, 1980 are subject to the payment of maintenance fees which must be paid to maintain the patent in force. These fees are due at 3 ½, 7 ½ and 11 ½ years from the date the patent is granted and can be paid without a surcharge during the "window-period" which is the six month period preceding each due date, e.g., 3 years to 3 years and six months. (See fee schedule for a list of maintenance fees.)

Failure to pay the current maintenance fee on time may result in expiration of the patent. A 6-month grace period is provided when the maintenance fee may be paid with a surcharge. The grace period is the 6-month period immediately following the due date. The Patent and Trademark Office does not mail notices to patent owners that maintenance fees are due. If, however, the maintenance fee is not paid on time, efforts are made to remind the responsible party that the maintenance fee may be paid during the grace period with a surcharge.