Child Support?

i Pay child support been paying for a while now i owe about 20,000 dollars in back pay. is it any way that i can stop the state of Al fron taken my income tax check at the end of the year. when i'm paying on time for years. the state is saying i owe them for istance the mother receive back durning that time. also every time the balance is not paid in full im being charged 12% a yaear. My balance with the state started out at 5,000 dollars now it have went up to 20,000 because i havent made payments to the state but i pay my child support for the last 7 years and my kids are 9 years old