Texas Election Code - ELEC § 1.009. Time of Receipt of Mailed Document

(a) When this code provides that an application, notice, or other document or paper that is delivered, submitted, or filed by mail is considered to be delivered, submitted, or filed at the time of its receipt by the appropriate authority, the time of receipt is the time at which a post office employee:

(b) If the authority cannot determine the time at which a deposit under Subsection (a)(2) occurred or whether it occurred before a specified deadline, the deposit is considered to have occurred at the time the mailbox or usual place of mail delivery, as applicable, was last inspected for removal of mail.