Your question is divided into two parts:
A. How much will he be charged for child support? To answer this you need to calculate the Florida Child Support Guidelines. The result may differ depending on who is calculating them and the input you place in them. The child's mother's income must be considered, as well as your boyfriends. However, if there is an expense for care for the boy (day care expenses, after school care, etc.) and if there is health insurance premiums paid by the mother and/or by your boyfriend, the number must be included in the calculation. Also, if your boyfriend is paying child support for any other children, if he belongs to a mandatory union, if he has mandatory retirement taken off his paycheck, etc. So, he may want to sit down with a lawyer of his choice to do the calculations together so he can visualize how it is done. The mother's income must be known with some certainty to do the calculations.
Because of all those factors, it will be difficult for any lawyer at this site to give you a specific amount without looking at all the factors I have mentioned to you.
B. Will they take it all at once or will he be able to pay the back child support in payments? I have rarely seen a case where the judge will order him to pay all the back child support at once. Usually, the judge establishes a repayment plan (which could be 20% of the actual child support amount, for instance, and in addition to the child support).
I hope the answer helped,
Alejandro R. Lopez, Esq.
Law Office of Alejandro R. Lopez, P.A.
4465 Edgewater Drive,
Orlando, Fla. 32804
Ph.: (407) 649-1404
Fax: (407) 649-9890