I am suing someone for unpaid services rendered. I have there address at work but not their home address. Can I serve them at work?
Chapter 7 Bankruptcy Attorney
You can so long as you are the person who is owed the money. If you are a third party collector, or a law firm (you should know this) doing anything with the employer to collect a debt it might be construed as a fair debt collection practices law violation.
A defendant "can" usually be served pretty much anywhere (with exceptions), but the plaintiff himself can't do the serving, it has to be a third party.