Is a company allowed to lay people off the same day they hire back an ex employee who quite the company 3 months earlier?

They are, although if you have been laid off, you are owed severance. Use our Severance Pay Calculator (http://www.severancepaycalculator.com) to find out how much you may be owed, and give us a call to discuss the situation in more detail. We would be happy to help in any way we can.