Child support here in North Carolina is court ordered if a voluntary amount is not settled before an attorney. A judge determines the rate based on earnings of both parents etc.

In Australia - you are able to appeal the amount they take out

@nedkelly: Here in the U.S.A. state law governs this area. The calculations are based on state prescribed formulas and there is no appeal process that I am aware of. But I've only dealt with this from the employer side, so maybe the garnishee has some appeal recourse.

And government mandated amounts are just as SBelle said. I was talking about non governmental garnishment in my reply here.

iam asking in general

I like a sprig of parsley as my garnishment. Not that you asked.