The hours of operation are 7 a.m. The simplest way to get a copy of an EIN verification letter is to call the IRS.Follow the below process to obtain a tax ID verification letter. Use this tool to get an EIN directly from the IRS in minutes for free. Once the IRS issues an EIN for your Illinois LLC, you will receive your official approval, known as an EIN Confirmation Letter (CP 575). This confirmation letter is known as Form CP 575 and is mailed to the address mentioned in your Form SS-4 application. Electronically - Go to our website at MyTax.illinois. 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. When you apply for an EIN, you will receive a confirmation letter you should store in a safe place. Confirmation. You will receive your filing confirmation via email.