In any action in which a court child support order is issued or modified, in any other proceeding in which the court determines the amount of child support that will be ordered to be paid pursuant to a child support order, or when a child support enforcement agency determines the amount of child support that will be ordered to be paid pursuant to an administrative child support order, issues a new administrative child support order, or issues a modified administrative child support order, the court or agency shall calculate the amount of the parents’ child support and cash medical support in accordance with the basic child support schedule, the applicable worksheet, and the other provisions of Chapter 3119. of the Revised Code. The court or agency shall specify the support obligation as a monthly amount due and shall order the support obligation to be paid in periodic increments as it determines to be in the best interest of the children. In performing its duties under this section, the court or agency is not required to accept any calculations in a worksheet prepared by any party to the action or proceeding.