H1b status can be extended for a three-year period or shorter period because the foreign national can maintain this status for up to a total of six-year period. Extension request can be filed six months in advance. Upon filing the extension, the h1b worker is authorized to work for 240 days from the date of expiry of his or her h1b status if the extension request is timely filed which means that the request was filed before the previous h1b status expired.
In Badrawi v. U.S, 07-cv-01074-JCH, filed 4/12/11, the Federal Dist. Ct. Connecticut held that when an H1B worker filed a timely extension petition he is not removable upon expiry of his lawful stay. The Court held that under the Federal Regulations, such a worker is employment authorized for 240 days from the date of expiry of his status and that fairness and due process required that the foreign nationals who stay within U.S. be considered authorized by the regulations.
AC21 porting or 7th year extension: Exceptions to 6-year h1b period limit applies to those h1b holders on whose behalf the employer has filed an immigrant visa petition in I-140 or labor certification that is pending for 365 days or more before the extension request is filed, or the I-140 is filed and approved.