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Pagina extraida do site do escritorio advocaticio Carl Shusterman
Initially, you may obtain H-1B status for up to three years. Prior to the expiration of the three-year period, you may apply to extend your stay for an additional three years. At the end of the six year period, no further extensions of H-1B status are permitted. Although you are allowed to change employers by submitting a new petition to INS (accompanied by a new LCA from DOL), this does not waive the six-year limitation.
Should you wish to apply for permanent residence, you should begin this process as early as possible after you have located satisfactory employment.