Like dm....the agreement on who pays what was done and signed PRIOR to the divorce. He left end of January, the agreement was signed and institued on 2/19 (D wasn't until July).
We did not do the state calculation for CS. Attorney recommended an amount, DH covers their med/dental (we split the deductibles, etc 50/50). We also split all school and extracurricular activities.
You can put anything (and any amount) in your agreement. You do not have to use the state calculator.
HOWEVER....once you have your agreement done, still file it with domestic relations. They will still process the payments directly from him.
This way you do not have to deal with him and if there is ever an issue with him not paying CS - they are in a position to help you.
Edited: Address EVERYTHING you can think of in the agreement (tuition, uniform, sports, school trips, etc)...this saves you having to bicker about every little think down the line. I just mail him a statement each month with the invoices for sports and what is half is.