Unless otherwise provided, references to "days" in this chapter mean calendar days. For purposes of determining timeliness of filing and receipt of documents transmitted by mail, 3 days shall be presumed added to the prescribed period. If the last day for filing a document is a Saturday, Sunday or legal holiday, the time for filing shall be extended to the next business day. Transmittal by mail means by first-class mail.
34 Pa. Code § 127.2