Federal laws in the U.S. normally require that employees work more than forty hours per week to receive an overtime pay. The overtime is considered at the usual hourly rate of pay plus an additional 50% of that normal rate. If you are paid weekly, bi-weekly or a monthly salary, it does not mean that you are not allowed to have overtime pay. If you do not want to be allowed for overtime, you must be in an exempt classification, which are: executive, organizational or specialized employees. Additionally, you have to pass an exam consisting of two parts: income basis information and a duties test.
The requirements you need to be an executive employee are: you must be customarily and frequently directing the job of two or more other full time workers. You must have the power to employ and fire, have management as your main responsibility, and not spend more than 20% in activities that are not directly involved with the main job. To be excused as an administrative employee you must cover as administrative tasks as your main duty, customarily and habitually exercise discretion and independent judgment and also not spend more than 20% of the work time in activities that not directly involved with the main job.
Finally, to be exempt as a professional employee you must have as your main obligation, a job that requires education, originality and creativity in a known field or teaching. If you or some one you know is payable unpaid overtime, you qualify for damages or compensations. Contact your attorney and ask for more information about this case.