Texas Family Code - FAM § 154.122. Application of Guidelines Rebuttably Presumed in Best Interest of Child

(a) The amount of a periodic child support payment established by the child support guidelines in effect in this state at the time of the hearing is presumed to be reasonable, and an order of support conforming to the guidelines is presumed to be in the best interest of the child.

(b) A court may determine that the application of the guidelines would be unjust or inappropriate under the circumstances.