Can a severance pay check be garnished?

Generally, there are few payments/bank accounts that a creditor cannot garnish. For example, federal income tax refunds cannot be garnished by a state court until the amount has been paid over. Garnishments typically stem from a judgment against a person in civil court (though there are one or two other processes) meaning someone probably sued you for a debt and they won, or you didn't show up, which amounts to the same thing. That's bad, but it also means that whoever sued you initially had to follow a particular procedure. I would suggest you talk to a local attorney and take them all the paper you've been sent by this creditor. It's always possible that the correct procedure was not followed, which may give you an out.