A work permit is commonly called the Employment authorization document (EAD) in USA. The Employment Authorization Document (EAD) is a US-issued card. Citizenship and Immigration services enable the foreign national card holder to work in the United States.
For work in L-1 status, a L-1 Visa is required. This is a Non-immigrant visa and is valid for 3 months to 5 years for a relatively short period of time. The average period is seven years for extensions. Staff of an international company with offices both in the USA and abroad may obtain a L-1 visa. The visa requires these foreign workers to move to the US office of the business after being working abroad for at least a year before their entry to the USA in the past three years. American and
non-US employees are to be related in one of four ways: the parent and subsidiaries; offices and registered offices; sister enterprises of joint parent ownership or "affiliates" of one or more of the same or of individuals at roughly equal proportions.Spouses of the holders of the L-1 visa shall be allowed without any restriction to work in the US (with the grant of the visa of L-2), once EAD is issued.