The IRS Form CP 575 is the letter you received from the IRS granting your Employer Identification Number. In lieu of the IRS Form CP 575, the applicant may use any official correspondence, such as the quarterly tax payment coupon, from the IRS showing the name of the entity as shown on the application and the EIN.
An Employer Identification Number (EIN) is also known as a Federal Tax Identification Number, and is used to identify a business entity. Please see mor edetails in the IRS publication 1635 - http://www.irs.gov/pub/irs-pdf/p1635.pdf
Generally, businesses need an EIN. You may apply for an EIN in various ways, and now you may apply online. This is a free service offered by the Internal Revenue Service.
Taxpayers can obtain an EIN immediately by calling the Business & Specialty Tax Line at(NNN) NNN-NNNN The hours of operation are 7:00 a.m. - 10:00 p.m. local time, Monday through Friday. An assistor takes the information, assigns the EIN, and provides the number to an authorized individual over the telephone.
Taxpayers can FAX the completed Form SS-4 application to their state FAX number (see Where to File - Business Forms and Filing Addresses), after ensuring that the Form SS-4 contains all of the required information. If it is determined that the entity needs a new EIN, one will be assigned using the appropriate procedures for the entity type. If the taxpayer's fax number is XXXXX a fax will be sent back with the EIN within four (4) business days.
The processing timeframe for an EIN application received by mail is four weeks. Ensure that the Form SS-4 contains all of the required information. If it is determined that the entity needs a new EIN, one will be assigned using the appropriate procedures for the entity type and mailed to the taxpayer.