A B-1 visitor visa is a temporary (nonimmigrant) visa for persons on business.  Depending on the purpose/plan of the visitor, the B-1 visa holder may get authorized period of stay from ten days to six months.

A B-1 visitor is generally invited by a US company which has issued a letter of invitation to the foreign visitor.

A B-1 visitor can extend his/her stay in the United States by filing the application to extend the authorized stay with US INS before the expiration of his/her status.

A B-1 visitor can apply for change to other nonimmigrant status, such as H-1 worker status or F-1 student status.  Due to the relative short period of stay originally authorized by US INS officer, it is not easy to obtain the approval for change of status.  But The approvals for such applications do occur.

If you are a B-1 visitor and you want to extend your stay or change to other status, please contact us as early as you can after you arrive in the United States.

But how do I know when my authorized stay expires?