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. The hours of operation are 7 a.m.The EIN approval process can take up to 2 weeks. Once the IRS issues an EIN for your Arizona LLC, you will receive your official approval, known as an EIN Confirmation Letter (CP 575). EIN confirmation letter is typically a tax ID certificate. 10. State how you would like to receive your confirmation letter. When prompted, select option "4" for "Employer Identification Numbers (EIN). Before you begin the EIN verification process, remember that if you have Form CP 575, you already have the confirmation notice. Employers withholding income tax from employees in Arizona must register their Employer Identification Number (EIN) with ADOR to file withholding returns. Online: Filling for an EIN online is the preferred method for both the IRS and individuals as once the application has been submitted an EIN is issued.