Provisions made under the American Competitive Act for the H1B temporary worker
The Immigration Act of 1990 imposed the 6-year rule. H1B status is valid for a maximum of six years. As with every rule there are certain exceptions. Changing from H to L status at the end of the 6th year cannot extend the 6 years. It may, however, be possible to change to L status earlier.
Ability to start work upon filing the H1B petition
Prior to October 17, 2000, an H1B beneficiary was not allowed to work until the CIS had approved the H1B petition. Under ACTA, a person who is already in H1B status is allowed to accept new employment and start working for the new employer immediately upon filing the H1B petition as long as the person satisfies all of the following three criteria:
1] Has been lawfully admitted to the U.S.,
2] Filed a non-frivolous H1B or other non-immigrant petition which is pending for new employment; and
3] Has never been employed without authorization in the U.S. before the filing of the H1B petition.
To read more download American Work permit – Official Rules & Regulations of American Work Visa