When this chapter requires a notice, report, or other document or paper to be delivered, submitted, or filed within a specified period or before a specified deadline, a delivery, submission, or filing by first-class United States mail is timely except as otherwise provided by this chapter, if:
  (1) it is properly addressed with postage prepaid; and
  (2) it bears a post office cancellation mark indicating a time within the period or before the deadline, or if the person required to take the action furnishes satisfactory proof that it was deposited within in the mail within the period or before the deadline.

Source Note: The provisions of this §20.23 adopted to be effective December 31, 1993, 18 TexReg 9714