Tex. Transp. Code § 521.298

If, not later than the 15th day after the date on which the person is considered to have received notice of the suspension or revocation under Section 521.295(b), the department receives at its headquarters in Austin, in writing, including a facsimile transmission, or by another manner prescribed by the department, a request that a hearing be held, a hearing shall be held as provided by Sections 521.295-521.303.