Can property owned by both myself and my second wife be seized for back child support?
It is possible for joint assets to be seized in payment of one owner's debt for back child support. The lien would be effective for the payer's equity interest up to the amount of support arrears. For example, a house titled jointly may be sold and the child support collected out of the proceeds of the sale up to the amount of the debtor's ownership interest in the property.
Married persons can hold property in a special form of concurrent ownership called "tenants by the entireties." The benefit of tenants by the entireties is that a spouse's separate creditors are barred from reaching the property by a legal construct called the "marital unity." The Supreme Court has decided that this long-established rule of law is fine for everyone but the Internal Revenue Service.