19 Tex. Admin. Code § 89.45
An examinee who fails to achieve a minimum passing score on one or more of the tests may retest on the tests he or she failed, except for instances in which the American Council on Education establishes that scores may not be combined across a General Educational Development test series, in which case the examinee must successfully complete the full battery of tests in a series. A person desiring to retest must wait six months to do so unless he or she presents a letter from an adult preparation program or a certified teacher verifying that the individual is prepared to retest. Each retest must be on a different form of the test.
Source Note:The provisions of this §89.45 adopted to be effective September 1, 1996, 21 TexReg 5690; amended to be effective April 18, 2002, 27 TexReg 3061.