The IWO is the OMBapproved form (PDF) used for income withholding in tribal, intrastate, and interstate cases as well as all child support orders. This form is used to request the issuance of income withholding for support.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. For more information regarding direct deposit, please call toll free to the Child Support Customer Service Unit at. What paperwork do I need to modify my child support with the court? Can I file a child support modification online? Federal law also: requires employers to comply with income withholding orders from other states. You can claim the Child Tax Credit for each qualifying child who has a Social Security number that is valid for employment in the United States.