Child maintenance is a monthly payment made to the primary carer of the children by the non-resident parent. It is a statutory liability so the non-resident parent must pay child maintenance to assist with the costs of the children. The parties can either agree the amount that will be paid each month, or apply to the Child Maintenance Service to assist. The Child Maintenance Service will apply a formula based on the number of nights per week that the children spend with the non-resident parent and their gross weekly salary.