Obtaining a visa to enter the United States does not guarantee that a foreign national will be allowed entry and thus obtain a valid immigrant or non-immigrant status. For L-1 Visa holders, like any other visa holder, requests for admission to the United States are made at the border upon arrival at a U.S. port of entry.
The alien seeking admission must have a valid passport with an L visa stamp. The alien should also have the approval notice of the L-1 petition, a copy of the petition, and supporting letter with them at the entry port.
If the immigration officer decides to admit the visa holder, the officer will place a stamp in the passport noting the admission and the period of authorized stay. The immigration officer will also annotate Form I-94, or an Arrival and Departure Record.
In order to maintain valid L status during their stay in the United States, an alien must work for the employer that petitioned for their L status and in the capacity specified in the petition letter and cannot work for another employer. For L-1A this means in a managerial or executive capacity and for L-1B this means in a specialized knowledge capacity. An alien in L status may attend an academic institution without explicit approval from the USCIS if such enrollment is limited and incidental to the authorized employment. If an alien in L status would like to stay in the United States longer than what their authorized stay allows at that time, they need to file an extension request with the USCIS before their authorized stay expires. Failure to do so will risk their stay and future re-entry into the United States.