What is the fastest legitimate way to get an EIN for free?

Apply directly through the IRS online EIN Assistant at irs.gov, which issues the number immediately at the end of the session, at no cost. It is available to applicants whose responsible party has an SSN or ITIN, during posted hours, and you must finish in one sitting. If you cannot use the online tool, faxing Form SS-4 returns an EIN in about four business days, and mail takes several weeks. Avoid the many lookalike websites that charge $50 to $300 to 'obtain' an EIN for you; they simply file the free form the IRS offers directly. The IRS never charges for an EIN, so any fee is pure markup on a free government service.