The difference is that child support is a court ruling. This would just take the IRS to file a notice, even if it's incorrect.
List of Obama cabinet members who owe back taxes:
Hilda Solis’s husband
A new report just out from the Internal Revenue Service reveals that 36 of President Obama’s executive office staff owe the country $833,970 in back taxes. These people working for Mr. Fair Share apparently haven’t paid any share, let alone their fair share.