There is no maximum period for O-1 status. Theoretically, it can be indefinite. However, the length of the status is determined by the length of time needed for the alien to perform his/her duties or activities with the US employer.
An initial stay is limited to no more than three years, provided the petition can establish that the O-1 alien will need this much time for the proposed employment. This period may be extended at one-year increments thereafter, upon evidence showing that the alien's continued presence would be required.
