The law requires that ORS use income withholding as the default way of paying child support. The IWO is the OMBapproved form (PDF) used for income withholding in tribal, intrastate, and interstate cases as well as all child support orders.For other case types you can use the Child Support Calculator or the fill-in-the-blank forms in the forms section below. This form is used to notify an employer to withhold wages from a noncustodial parent when they have past-due child support. View the form in English. Complete Form W-4 so that your employer can withhold the correct federal income tax from your pay. Give Form W-4 to your employer. Wage withholding lets you make your child support payments through your regular paycheck. Other items you may find useful. Finally, the parent filling out the form must indicate which parent is the plaintiff for the child support action.