(a) The court may not add any portion of the net resources of a new spouse to the net resources of an obligor or obligee in order to calculate the amount of child support to be ordered in a suit for modification.
(b) The court may not subtract the needs of a new spouse, or of a dependent of a new spouse, from the net resources of the obligor or obligee in a suit for modification.
Official text of the Texas Family Code as published by the Texas Legislative Council.