What is the fastest reason to apply for an ITIN?

The fastest way to get an ITIN application approved is by using the following reason:

Owners of a U.S. LLC with 2 owners or more:

1(a) Individuals who are partners of a U.S. or foreign partnership that invests in the United States and that owns assets that generate income subject to IRS information reporting and federal tax withholding requirements

Why this is the fastest way?

Because it does not require any 3rd party documents, such us - bank letters, employment letters, government letters. The required documents can be obtained within days and via email.​