(1) In a proceeding for dissolution of marriage or domestic partnership, legal separation, declaration of invalidity, maintenance, or child support, after considering all relevant factors but without regard to misconduct, the court shall order either or both parents owing a duty of support to any child of the marriage or the domestic partnership dependent upon either or both spouses or domestic partners to pay an amount determined under chapter 26.19 RCW.
(2) The court may require automatic periodic adjustments or modifications of child support. That portion of any decree that requires periodic adjustments or modifications of child support shall use the provisions in chapter 26.19 RCW as the basis for the adjustment or modification. Provisions in the decree for periodic adjustment or modification shall not conflict with RCW 26.09.170 except that the decree may require periodic adjustments or modifications of support more frequently than the time periods established pursuant to RCW 26.09.170.
(3) Upon motion of a party and without a substantial change of circumstances, the court shall modify the decree to comply with subsection (2) of this section as to installments accruing subsequent to entry of the court's order on the motion for modification.
(4) The adjustment or modification provision may be modified by the court due to economic hardship consistent with the provisions of *RCW 26.09.170(6)(a).