The terms of certain patents may be subject to extension or adjustment. Such extension or adjustment results from certain specified types of delays that may occur while an application is pending before the office. The USPTO will issue an accounting of the extension with the notice of allowance.
The issuance of the patent does not necessarily mean that an applicant will not have to pay additional fees. All utility patents that issue from applications filed on and after December 12, 1980 are subject to the payment of maintenance fees, which are required to maintain the patent in force. These fees are due at 3 1/2, 7 1/2 and 11 1/2 years from the date the patent is granted.
The failure to pay a maintenance fee on time may result in expiration of the patent. A six-month grace period is provided when the maintenance fee may be paid with a surcharge. The grace period is the six-month period immediately following the due date. The USPTO 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.