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.Use this tool to get an EIN directly from the IRS in minutes for free. 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. If you apply online, you can download the EIN Confirmation Letter at the end. How to Contact the IRS for EIN Verification Letter? Obtained your tax ID number. However, it will be a letter on IRS letterhead informing your business of the request being made for a copy of your EIN number. If the signer does not have an SSN, the employer identification number (EIN) of the entity can be used.