From experience, Piglet's math isn't quite right (sorry piglet). Statutorily there is a formula that is based on total income, income percentages, number of children and percentage of time that your D is with each of you. The bottom line is it isn't just income X percentage.
Piglet is right, you need to have the support court managed. Personally, I am not required to do that, but if I am more than 15 days late one time, CW can make me pay through the courts, which I pay an additional fee. In your sitch, I would push to have the courts facilitate the payment.
There is negotiation to the support amount as well. Generally the support cannot go above the statutory requirement, but you can negotiate it....I did and I am paying below the requirement.
Me: 44 S: 17 and 7 Final-6-13-08 I once went to a psychic who told me I would soon feel cheated......