Texas Code of Criminal Procedure - CRIM P Art. 28.10. Amendment of indictment or information

(a) After notice to the defendant, a matter of form or substance in an indictment or information may be amended at any time before the date the trial on the merits commences. On the request of the defendant, the court shall allow the defendant not less than 10 days, or a shorter period if requested by the defendant, to respond to the amended indictment or information.

(b) A matter of form or substance in an indictment or information may also be amended after the trial on the merits commences if the defendant does not object.

(c) An indictment or information may not be amended over the defendant's objection as to form or substance if the amended indictment or information charges the defendant with an additional or different offense or if the substantial rights of the defendant are prejudiced.