50 C.F.R. § 222.304
When the permit is renewable and a permittee intends to continue the activity described in the permit during any portion of the year ensuing its expiration, the permittee shall, unless otherwise notified in writing by the Assistant Administrator, file a request for permit renewal, together with a certified statement, verifying that the information in the original application is still currently correct. If the information is incorrect the permittee shall file a statement of all changes in the original application, accompanied by any required fee at least 30 days prior to the expiration of the permit. Any person holding a valid renewable permit, who has complied with the foregoing provision of this section, may continue such activities as were authorized by the expired permit until the renewal application is acted upon.
50 C.F.R. § 222.304