Tex. Education Code § 12.0531

If a charter is granted under this subchapter, the board of trustees of the school district that granted the charter shall enter into a performance contract with the principal or equivalent chief operating officer of the campus or program. The performance contract must specify enhanced authority granted to the principal or equivalent officer in order to achieve the academic goals that must be met by campus or program students. A charter granted under this subchapter expires 10 years from the date the charter is granted unless the specified goals are substantially met, as determined by the board of trustees of the school district that granted the charter.