Salary or hourly? It is only mandatory for salary people in SOME states I think. Then too, the definition of mandatory varies. In some cases, overtime is considered to be "voluntary" and not subject to additional pay for salary people, but if the company consistently abuses salary people by FORCING them to work overtime, they can get additional pay. I know companies have abused salary people in the past and been sued for overtime pay and they lost. Most salary people are afraid to rock the boat. I once worked as a CWI/Welding Engineer for only $24K salary. My record weeks during a plant launch topped 104 hrs! (That was $4.43 per hour!) I got NO additional pay, and promptly found a country club 40hr salary job with a 10% raise!