(1) The amount of prospective child support is equal to the amount granted by a prior child support order unless:
(a) there is a substantial change of circumstances on the part of the obligor or obligee as described in this section; or
(b) an adjustment is made as described in this section or Section 81-6-213.
(2) If the prior child support order contains a stipulated provision for the automatic adjustment for prospective child support, the prospective child support is the amount as stated in the order, without a showing of a substantial change of circumstances, if the stipulated provision:
(a) is clear and unambiguous;
(b) is self-executing;
(c) provides for child support that equals or exceeds the base child support award required by the child support guidelines; and
(d) does not allow a decrease in child support as a result of the obligor's voluntary reduction of income.
(3)
(a) A parent, legal guardian, or the office may, at any time, petition the court to adjust the amount of a child support order if there has been a substantial change in circumstances.
(b) A change in the child support tables is not a substantial change in circumstances for the purposes of Subsection (3)(a).
(c) For purposes of this Subsection (3)(a), a substantial change in circumstances may include:
(i) material changes in custody;
(ii) material changes in the relative wealth or assets of the parties;
(iii) material changes of 30% or more in the income of a parent;
(iv) material changes in the employment potential and ability of a parent to earn;
(v) material changes in the medical needs of the child; or
(vi) material changes in the legal responsibilities of either parent for the support of others.
(4) Upon receiving a petition under Subsection (3)(a), the court shall, taking into account the best interests of the child:
(a) determine whether a substantial change has occurred;
(b) if a substantial change has occurred, determine whether the change results in a difference of 15% or more between the obligor's ordered support amount and the obligor's support amount that would be required under the child support guidelines; and
(c) adjust the obligor's ordered support amount to that which is provided for in the child support guidelines if:
(i) there is a difference of 15% or more; and
(ii) the difference is not of a temporary nature.
(5)
(a) If a child support order has not been issued or modified within the previous three years, a parent, legal guardian, or the office may move the court to adjust the amount of a child support order.
(b) Upon receiving a motion under Subsection (5)(a), the court shall, taking into account the best interests of the child:
(i) determine whether there is a difference between the obligor's ordered support amount and the obligor's support amount that would be required under the child support guidelines; and
(ii) if there is a difference as described in Subsection (5)(b)(i), adjust the obligor's ordered support amount to the obligor's support amount provided in the child support guidelines if:
(A) the difference is 10% or more;
(B) the difference is not of a temporary nature; and
(C) the order adjusting the obligor's ordered support amount does not deviate from the child support guidelines.
(c) A showing of a substantial change in circumstances is not necessary for an adjustment under this Subsection (5).