Although some state laws (e.g., California's) provide otherwise, there is no limit placed by federal law on how many days in a row an employer can require en employee to work, nor (on most jobs) how many hours in a day an employer can require an employee work. Generally, if the employer is covered by the FLSA, the restriction on the number of days or hours that an employee works is an economic one. That is, the employer has to pay the employee premium pay (1.5 x the employee's regular hourly pay rate) for all hours the employee works over 40 hours in a 7 consecutive day pay period. he does not have such restrictions or requirements if the employee is "exempt" from overtime pay eligibility. There are over 200 exemptions. The most common are the ":white collar exemptions (professional employee; executive employee; or administrative employee). These three exemptions have precise definitions that are very narrow, and the employer must prove that the employee satisfies every part of the exemption. One requirement that all three exemptions have in common is that, to be considered exempt from overtime pay coverage, the employee must be genuinely salaried. That means that the employee's pay cannot fluctuate according to the number of hours or days that the employee works in a work week. If the employee works 15 minutes in a work week, the salaried employee must be paid the whole salary. If the pay fluctuates because the employee has missed a day of work, then the employee is not salaried. If the employee is not salaried then he must be paid overtime. There are other wrinkles in this law too, including the :fluctuating work week pay method of calculation which is beyond your question.