Texas Government Code - GOV'T § 823.002. Service Creditable in a Year

(a) The board of trustees by rule shall determine how much service in any year is equivalent to one year of service credit, but in no case may all of a person's service in one school year be creditable as more than one year of service.  Service that has been credited by the retirement system on annual statements for a period of five or more years may not be deleted or corrected because of an error in crediting unless the error concerns three or more years of service credit or was caused by fraud.

(b) A member shall notify the retirement system in writing of membership service that has not been properly credited by the retirement system on an annual statement.  The member must provide verification and make deposits as required by the retirement system before the service may be credited.  A member must notify the retirement system of the service in writing on or before the last day of the fifth school year after the end of the school year in which the service was rendered for the service to be credited.