27 CFR § 31.115 - Employer identification number.
(a) Requirement. The employer identification number (as defined in 26 CFR 301.7701–12) of a dealer who has been assigned such a number must be shown on each registration form filed under this part. A dealer who does not have such a number must apply for one as provided in paragraph (b) of this section and enter “number applied for” in the space for the number on the registration form; then, upon receipt of the number from the Internal Revenue Service, the dealer must provide it to TTB by separate correspondence. Failure of a dealer to include the employer identification number may result in the imposition of the penalty specified in § 31.14(b).
(b) Application for employer identification number. Each dealer who files a registration form and who has not already been assigned an employer identification number must file Internal Revenue Service (IRS) Form SS–4 to apply for one. The dealer shall apply for and be assigned only one employer identification number, regardless of the number of places of business for which the dealer is required to file a registration form under this part. The employer identification number shall be applied for no later than 7 days after the filing of the taxpayer's first registration form. IRS Form SS–4 may be obtained from the director of an IRS service center, from any IRS district director, from http://www.irs.gov/, or from TTB's National Revenue Center.