(a) The executive commissioner by rule shall establish a sliding fee schedule for the payment by the resident’s parents of the state’s total costs for the support, maintenance, and treatment of a resident younger than 18 years of age.
(b) The executive commissioner by rule shall set the fee according to the parents’ net taxable income and ability to pay.

(c) The parents may elect to have their net taxable income determined by their most current financial statement or federal income tax return.
(d) In determining the portion of the costs of the resident’s support, maintenance, and treatment that the parents are required to pay, the department, in accordance with rules adopted by the executive commissioner, shall adjust, when appropriate, the payment required under the fee schedule to allow for consideration of other factors affecting the ability of the parents to pay.
(e) The executive commissioner shall evaluate and, if necessary, revise the fee schedule at least once every five years.