Generally if you are required to work more than 8 hours in a day or 40 hours in a week, your employer is required to pay you overtime. In some jurisdictions like California, if you have to work more than 12 hours in one day you are entitled to double time. The way overtime is calculated changes from state to state so you should consult the Department of Labor in your state for details of overtime in your state. Best of luck!
NO LEGAL ADVICE GIVEN. READ THIS BEFORE you contact me! My responses to questions on Avvo are never intended as legal advice and must not be relied upon as if they were legal advice. I give legal advice ONLY in the course of a formal attorney-client relationship set forth in a written document executed by the client and by me or a member of my firm. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. My law firm does NOT provide free consultations. Please do not call or write to me with a “few questions” that require me to analyze the specific facts of your history and your case. I can give advice, make recommendations and answer specific questions only after reviewing the evidence and documents applicable to a specific client and following a personal meeting in my office in which the relevant facts can be developed and analyzed. My law firm presently accepts cases involving State and federal administrative law; professional licenses and permits; education law; employment and labor law; and litigation matters in state and federal courts. Our practice is limited to the States of Oregon and California. If you have a case in any other state we would not be able to assist you. Unless we have a signed written fee agreement you are not my or my firm's client.
In the typical situation, there is no prohibition against the employer adjusting the schedule to avoid employees working more than 40 hours of work. An exception would be where a collective bargaining agreement has restrictions specifying the hours of work for each shift. I am assuming you are eligible for overtime to begin with.
Generally, if you are entitled to overtime (some jobs aren't anyway), then you are entitled to overtime for time over 40 hours in a week. "Overtime" is not more than 8 hours in a day. It is simply if you work more than 40 hours in a week. The Department of Labor website has some good guidelines that will help address your question also.
DISCLAIMER: My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.