Check the IRS EIN confirmation letter if you already received one
Review prior tax returns, payroll records, or business formation documents
Contact your bank or lender if you used the EIN for business accounts or loans
Search your business email for IRS correspondence or application records
Call the IRS Business and Specialty Tax Line at 800-829-4933
Ask your accountant, bookkeeper, or payroll provider
Check state business registration records if the EIN was filed there
Use the IRS online EIN application records if you applied recently and saved the confirmation
Request a copy of your EIN assignment letter from the IRS if needed