12 CFR §1102.27

1. (a)General rule. In computing any period of time prescribed or allowed by this subpart, the date of the act, event or default from which the designated period of time begins to run is not included. The last day so computed is included, unless it is a Saturday, Sunday, or Federal holiday, in which event the period runs until the end of the next day which is not a Saturday, Sunday or Federal holiday. Intermediate Saturdays, Sundays, and Federal holidays shall not be included in the computation.
2. (b)For service and filing responsive papers. Whenever a time limit is measured by a prescribed period from the service of any notice or paper, the applicable time periods are calculated as follows:
   1. (1)If service is made by first class, registered or certified mail, add three days to the prescribed period; and
   2. (2)If service is made by express mail or overnight delivery service, add one day to the prescribed period.