Nonimmigrants who wish to visit the US for business must obtain a B1 visa to enter the United States. Generally these visas are valid for five to ten years. However, the visa holder is only allowed to remain in the US while his or her I-94 card is valid. B1 holders should return to their home country or apply for a visa extension before their I-94 card expires. Failure to extend the visa or return home can result in the current visa being revoked and future visa applications being denied.