You're violating the law if you're acting as their employer.

 

If they are operating their own businesses, then the onus is on them to pay both halves of the SS tax.

 

In no instance is it lawful for anyone to earn wages and not have SS withheld. Whether the worker is or isn't an ILLEGUL has nothing to do with it. That's why the outrage expressed in this thread's title is so STOOOPID