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. How to Contact the IRS for EIN Verification Letter? This article will cover everything you need to know about EINs and what to do if you lose your EIN confirmation letter from the IRS. Gov(opens in a new window). 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. The easiest and most convenient way to apply for your EIN is the EIN online portal at IRS.gov. You can complete form ss-4 and mail or fax it. Click here to to view additional information on tax rates and changes.