20 CFR § 725.311 - Communications with respect to claims; time computations.
(a) Unless otherwise specified by this part, all requests, responses, notices, decisions, orders, or other communications required or permitted by this part shall be in writing.
(b) If required by this part, any document, brief, or other statement submitted in connection with the adjudication of a claim under this part shall be sent to each party to the claim by the submitting party. If proof of service is required with respect to any communication, such proof of service shall be submitted to the appropriate adjudication officer and filed as part of the claim record.
(c) In computing any period of time described in this part, by any applicable statute, or by the order of any adjudication officer, the day of the act or event from which the designated period of time begins to run shall not be included. The last day of the period shall be included unless it is a Saturday, Sunday, or legal holiday, in which event the period extends until the next day which is not a Saturday, Sunday, or legal holiday. “Legal holiday” includes New Year's Day, Birthday of Martin Luther King, Jr., Washington's Birthday, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day, Christmas Day and any other day appointed as a holiday by the President or the Congress of the United States.
(d) In computing any period of time described in this part in which the period within which to file a response commences upon receipt of a document, it shall be presumed, in the absence of evidence to the contrary, that the document was received on the seventh day after it was mailed. In any case in which a provision of this part requires a document to be sent to a person or party by certified mail, and the document is not sent by certified mail, but the person or party actually received the document, the document shall be deemed to have been sent in compliance with the provisions of this part. In such a case, any time period which commences upon the service of the document shall commence on the date the document was received.