There will be more emphasis on "Family Based Arrangements" - which is absolutely fine if everything is amicable, but of course most people resort to the CSA precisely because that simply isn't possible. It seems the Government thinks that absent parents would rather hand over the money they should rightfully pay to the resident parent of their children rather than any Government agency. However the determined non-paying parent seems to be characterised by a willingness to pay anyone but the resident parent - whether that is a Government agency or an expensive lawyer.
Those who need to pursue an absent/non-resident parent (NRP) for maintenance if they are reluctant, sporadic or non-payers will probably have the same problems they always had. However, the move to a Gross Income Calculation (GIC) may make a difference to some NRP's who deliberately hide their real income by providing a misleading net income figure. The whole reason for the move to the GIC is that a record of gross income can be checked through HMRC returns.
Contributions to an occupational pension scheme will be excluded, but not if they are at a rate which is deliberately extortionate to avoid the payment of Child Maintenance.
As the percentages have also been changed, there is little difference to the actual amount of CM which will be payable, so the CM Calculator on the CM Options site still asks for net income, and points out that it is a guide only.
So, from 10 December 2012 if you are a new applicant with four or more children who have the same parents, you will be one of the first to "enjoy" the benefits of the new scheme. You apply to the CSA (Child Support Agency), and if you are an "appropriate" case, you'll be referred on to the CMS (Child Maintenance Service).
The existing and new schemes will run alongside each other for about 3 years, during which time the CSA will be closing existing cases under the old scheme and gradually transferring them to the new. Eventually, when all the software/IT issues are ironed out (if indeed that's possible) the scheme will cover all applicants, old and new.
At that point, it is anticipated that further changes will be introduced. New applicants will be charged a fee for the service, and attend an interview to show what steps you have taken between you to try to agree a "Family Based Arrangement" and resolve any issues between you.
You can read about the campaign against charges for CSA assistance, and find out how to get involved here on the Gingerbread website