It starts with your gross income, which includes overtime and part-time jobs, and use the Attorney General’s tax chart to compute your net income. Assuming you have no other children from previous relationships, you will pay 20% of your net income for one child, 25% for two children, 30% for three children and 35% for four children. There are caps and certain special circumstances where you may be ordered to pay more or less. For example, if the child is handicapped and will never be capable of supporting themselves.