The federal government provides financial assistance to states to collect local and interstate child support obligations. States have enacted a wide variety of methods to collect child support from those who are obligated to pay and fail or refuse to do so.

If the person who is required to pay child support (the "payor") fails to do so, a motion for contempt may be brought against him or her by the person who was suppose to receive it. The person entitled to receive child support only needs to provide evidence that the child support was due and allege that it was not received. The payor is then required to prove either that it was paid or that payment was excused. In some states, the fact that the payor is incarcerated is sufficient to excuse the payor from owing support during the months of incarceration. If the payor losses his job or becomes disabled, the payor may not just stop paying or reduce the amount of each payment. It is up to the payor to take steps to modify the amount of support owed, based on a change in circumstances. The payor will sometimes argue that the child spent additional time with the payor or that the child support was spent directly on the child., by way of clothing, a weekly allowance, or payment of expenses for the child. However, the payor does not have the right to pick and choose what he or she wants to pay and take credit for it.

Where the court finds that payment was excused, the payor will not be found in contempt. Where the payment is not excused, a court may find the payor to be in civil contempt. Where there is a pattern of continuing violations of the court's orders, a court can find the payor in criminal contempt rather than civil contempt. Civil contempt is intended to force compliance with the court order; criminal contempt is intended to punish the payor for past disobedience. The payor is entitled to present the same defenses whether the charge is for civil or criminal contempt.

When the court finds that the payor has failed to pay child support and that the payment was not excused, the court will require that the payor pay an additional amount in addition to the ongoing support obligation. The total amount is limited to the federal debt collection laws. Where the payor is found in contempt, a court may order incarceration. In civil contempt, incarceration may last until the arrearage is paid. Upon a finding of criminal contempt, the court can impose a sentence for a fixed period of time, regardless of whether the payor finds the funds to immediately pay the amount past due. In either situation, incarceration may provide for work release, where the payor continues to work during the day, but most of the paycheck goes toward paying off the arrearage. In addition to incarceration, the payor is may lose his license to drive a vehicle. The government can take any tax refund due the payor and use it to reduce any arrearage due. The court can also require that payment of child support be deducted from any wages or earnings due the payor. The amount of past due child support can be reduced to judgment, requiring the payment of interest on the amount past due. Child support payments cannot be discharged in bankruptcy.