Check your IRS EIN confirmation letter or CP 575 notice
Look for your EIN on any IRS tax documents (e.g., prior-year tax returns, correspondence)
Search your IRS business account online (if you have access)
Check your state business registration or business filing documents (sometimes includes EIN)
Review your bank account paperwork or business loan applications (may list your EIN)
Check your business formation documents or vendor onboarding forms (may include your EIN)
Contact the IRS Business & Specialty Tax Line and request your EIN verification (have your business details ready)