Child support payments can only be made retroactively for the last three years. When a final award of support is delayed, the courts issue retroactive child support. If a temporary child support order was not granted at the start of the case, retroactive support may be awarded. However, there are limits to how much support can be awarded retroactively. In California, parents must submit a Child Support Guidelines Form CS-42 or complete and file an affidavit based on information provided on the CS-42. The court will use this information to establish a support amount that it considers to be in the best interest of the children. If the parents cannot agree on a support amount, they will need to have a family law attorney help them through the process. Backchild support is support paid by a former spouse or partner for their previous offspring. Backchild support is different from forward child support in that backsupport goes toward reimbursing a parent for their share of uninsured medical expenses incurred on behalf of their previous child. Reimbursement for uninsured medical expenses is only available if the parent was ordered to pay such expenses by a judge or jury in a marital dissolution action or in a paternity action. Parents who have a consensual custody agreement or other type of agreement approved by the court can also request reimbursement for these expenses.