(1) When a child support order does not contain a per month per child amount, the division of child support (DCS) reviews the support order and other documents filed with the order in order to determine the amount of support due for each child. "Other documents" may include but are not limited to:

(a) The child support schedule worksheets which RCW 26.19.035(4) requires to be attached to or filed with the support order;

(b) Any residential schedule or parenting plan filed in the case where the support order was entered;

(c) Any findings of fact and conclusions of law filed in the case where the support order was entered; or

(d) Any other documents signed or approved by the tribunal which entered the child support order.

(2) DCS may consider the support amounts to be differentiated and determine a per-child amount to be paid by the noncustodial parent (NCP) if:

(a) The order or documents filed with the order reflect a per-child calculation and indicate the court intended to enter a per-child order, unless:

(i) There are expenses included in Part III of the child support schedule worksheet; or

(ii) The self-support reserve was applied, resulting in a monthly support obligation which is higher than the presumptive minimum support obligation; or

(iii) The forty-five percent limitation was applied in calculating the monthly support obligation; or

(iv) A deviation was granted because of children from other relationships; and

(b) The NCP's proportional share of all the per-child amounts equals the whole transfer payment amount.

(3) If DCS can determine a per-child amount of support, DCS determines the NCP's differentiated transfer payment by applying the NCP's proportional share of income (line six on the worksheet) to the basic support obligation for each child (line five on the worksheet). Example. Assume the support order states that NCP's transfer payment for three children is four hundred twenty dollars, but the order does not provide per-child support amounts. However, line six of the worksheet shows that the NCP's proportional share of income is .6 or sixty percent, and line five shows a basic support obligation of three hundred dollars for child number one, two hundred dollars for child number two and two hundred dollars for child number three. DCS can determine the NCP's support obligation to be one hundred eighty dollars (.6 x three hundred dollars) for child number one, and one hundred twenty dollars (.6 x two hundred dollars) each for child number two and child number three.

(4) When the NCP's support obligation for one or more, but not all, of the children covered by an undifferentiated support order is terminated for any reason, DCS determines whether the amount to be enforced for NCP's monthly support obligation under the order should change:

(a) If DCS is able to determine a per-month amount for each child, DCS may reduce the amount of the NCP's monthly obligation to be enforced by the per-month amount for each child who is no longer covered by the order.

(b) If DCS is unable to determine a per-month amount for each child, DCS continues to enforce the undifferentiated amount of support until there is no longer any child covered by the support order.