The employment based visa preference system allows American employers to petition the USCIS on behalf of certain qualifying employees. Preference categories are based around a numerical limit which determines the availability and waiting period of each preference category.

Many preference visa categories are oversubscribed. This means this system is often backlogged and employees often have to wait several years to be allocated a visa.

The preference categories are as follows:

First Preference (EB1)

Priority Workers, including aliens with extraordinary abilities, outstanding professors and researchers, and certain multinational executives and managers.

Second Preference (EB2)

Members of professions holding advanced degrees or persons of exceptional ability in the sciences, arts, or business who will substantially benefit the national economy, cultural or educational interests or welfare of America.

Third Preference (EB3)

Skilled workers, professionals and other qualified workers.

Fourth Preference (EB4)

Special immigrants (including ministers of religion).

Fifth Preference (EB5)

Investors (employment creation immigrants).

Schedule A Workers

Health care workers and aliens of exceptional ability.

The numerical limits decrease in order of preference, meaning the first preference is allocated more places for migration than the second preference and so on. The availability of each employment based visa is also limited by the employee's country of origin, as the Department of State will halt migration from a specific country once their quota for migration has been reached.