Tex. Education Code § 21.160

(a) A teacher employed under a continuing contract may relinquish the position and leave the employment of the district at the end of a school year without penalty by filing with the board of trustees or its designee a written resignation not later than the 45th day before the first day of instruction of the following school year. A written resignation mailed by prepaid certified or registered mail to the president of the board of trustees or the board's designee at the post office address of the district is considered filed at time of mailing.

(b) A teacher employed under a continuing contract may resign, with the consent of the board of trustees or the board's designee, at any other time.

(c) Subject to Subsections (e), (f), and (g), on written complaint by the employing district, the State Board for Educator Certification may impose sanctions against a teacher who is employed under a continuing contract that obligates the district to employ the person for the following school year and who:

(1) resigns;

(2) fails without good cause to comply with Subsection (a) or (b); and

(3) fails to perform the contract.

(d) If a school district submits a complaint regarding a teacher to the State Board for Educator Certification under Subsection (c), the district shall promptly notify the teacher of the complaint. The notice must include:

(1) the basis of the complaint;

(2) information regarding how the teacher may contact the State Board for Educator Certification; and

(3) a reminder that the teacher should verify that the teacher's mailing address on file with the State Board for Educator Certification is current.

(e) Before imposing sanctions against a teacher under Subsection (c), the State Board for Educator Certification:

(1) must consider any mitigating factors relevant to the teacher's conduct; and

(2) may consider alternatives to sanctions, including additional continuing education or training.

(f) If a teacher fails to timely file a written resignation as required by Subsection (a) but files a written resignation in the manner provided by that subsection not later than the 30th day before the first day of instruction of the following school year, the State Board for Educator Certification may not suspend or revoke the teacher's certificate under Subsection (c).

(g) The State Board for Educator Certification may not impose a sanction under Subsection (c) against a teacher who relinquishes a position under a continuing contract and leaves the employment of the district after the 45th day before the first day of instruction of the upcoming school year in violation of Subsection (a) and without the consent of the board of trustees under Subsection (b) if the teacher's failure to comply with Subsection (a) was due to:

(1) a serious illness or health condition of the teacher or a close family member of the teacher;

(2) the teacher's relocation because the teacher's spouse or a partner who resides with the teacher changes employers or location of employment;

(3) a significant change in the needs of the teacher's family in a manner that requires the teacher to:

(A) relocate; or

(B) forgo employment during a period of required employment under the teacher's contract; or

(4) the teacher's reasonable belief that the teacher had written permission from the school district's administration to resign.