37 CFR § 1.378 - Acceptance of delayed payment of maintenance fee in expired patent to reinstate patent.
(a) The Director may accept the payment of any maintenance fee due on a patent after expiration of the patent if, upon petition, the delay in payment of the maintenance fee is shown to the satisfaction of the Director to have been unintentional. If the Director accepts payment of the maintenance fee upon petition, the patent shall be considered as not having expired, but will be subject to the conditions set forth in 35 U.S.C. 41(c)(2).
(b) Any petition to accept an unintentionally delayed payment of a maintenance fee must include:
(1) The required maintenance fee set forth in § 1.20(e) through (g);
(2) The petition fee as set forth in § 1.17(m); and
(3) A statement that the delay in payment of the maintenance fee was unintentional. The Director may require additional information where there is a question whether the delay was unintentional.
(c) Any petition under this section must be signed in compliance with § 1.33(b).
(d) Reconsideration of a decision refusing to accept a delayed maintenance fee may be obtained by filing a petition for reconsideration within two months of the decision, or such other time as set in the decision refusing to accept the delayed payment of the maintenance fee.
(e) If the delayed payment of the maintenance fee is not accepted, the maintenance fee will be refunded following the decision on the petition for reconsideration, or after the expiration of the time for filing such a petition for reconsideration, if none is filed.