Well I dont know if the law in Ohio is differnet but most states if there is shared custody you wouldnt pay anything. Also, with all the stuff you pay now isnt it more then 300? The formulas are online to calculate it. If you have to pay support it just a flat amount not 300.00 and half of her other expenses etc. Becarefull because any money you pay her now is considered a gift and they could jack you and back date it.