Legal documentation required to obtain child support payments includes the custodial parent's photo ID and social security number, a copy of the birth certificate of each eligible child, any existing child support order and a divorce decree or separation agreement, if applicable, explains the U.S. Department of Health and Human Services' Office of Child Support Enforcement. The custodial parent also should provide legal records of child support received in the past and proof of income and assets.
A child support office may request additional legal forms, such as copies of tax returns, documentation of property holdings, bank account information and financial paperwork about investments, according to HHS' Office of Child Support Enforcement. Cases in which paternity is disputed may require a legal form and written statements that verify the noncustodial parent is biologically responsible for the child.
States such as Illinois may require custodial parents to complete an application to apply for child support if an existing order doesn't already exist, according to Illinois Child Support Services. Parents can complete an online application or visit a regional child support office to begin the process of establishing a child support order or to enforce an existing order. Laws regarding child support vary by state.