29 CFR § 801.71 - Filing and service.
(a) Filing. All documents submitted to the Secretary shall be filed with the Secretary of Labor, U.S. Department of Labor, Washington, DC 20210.
(b) Number of copies. An original and two copies of all documents shall be filed.
(c) Computation of time for delivery by mail. Documents are not deemed filed with the Secretary until actually received by the Secretary. All documents, including documents filed by mail, must be received by the Secretary either on or before the due date. No additional time shall be added where service of a document requiring action within a prescribed time thereafter was made by mail.
(d) Manner and proof of service. A copy of all documents filed with the Secretary shall be served upon all other parties involved in the proceeding. Service under this section shall be by personal delivery or by mail. Service by mail is deemed effected at the time of mailing to the last known address.