From a recent report by Social Security's Office of Inspector General (OIG):
SSA [Social Security Administration] could save approximately $151.2 million, annually, if the number of individuals receiving and/or reporting child support increases by 100,000. Alternatively, SSA could save approximately $302. million, annually, if the number of recipients receiving and/or reporting child support increases by 200,000. These dollar figures are conservative and are greatly reduced from figures we calculated assuming the results from 1999 SSA and Government Accountability Office studies are similar today
I think there are at least a couple of questions here. What would be the offsetting costs to state child support enforcement agencies? How willing would state child support enforcement agencies be to cooperate when cooperating won't necessarily save the states any money?