From Business Insider:
If you owe back child support — even back child support from decades ago — your Social Security check may be garnished under new U.S. Treasury rules.
The new rules, which were actually written to protect Social Security recipients from garnishment of other debts, has a loophole that allows child support orders to garnish — not just part — but all of the money in your bank accounts.
Margot Saunders, an attorney with the National Consumer Law Center, explains that under normal circumstances, federal law limits the maximum amount that can be administratively seized for both past-due and current child support to 65 percent of Social Security benefit.