The hours of operation are 7 a.m. The only two ways to get an EIN Verification Letter (147C) is to call the IRS at 1-800-829-4933, or to mail the IRS a written request.However, you will need Adobe Reader installed if you would like to receive a confirmation letter online. This confirmation letter is known as Form CP 575 and is mailed to the address mentioned in your Form SS-4 application. This EIN confirmation letter is called CP 575, and the IRS only mails the letter to the mailing address listed on line 4 of the SS-4 application. In the BIN field, type in your BIN number as indicated on your notice. The IRS sends out an EIN confirmation letter for every EIN application it processes. Employer Identification Number (EIN) document. An EIN is a unique nine-digit number that identifies a business for tax purposes. Organization Mission.