Check the company’s W-2, W-9, 1099, or tax forms
Ask the company’s payroll or accounting department
Review the company’s invoices, purchase orders, or vendor documents
Search the company’s SEC filings if it is publicly traded
Look up the company in state business registration records
Search the company’s website for tax or legal information
Contact the IRS if you are authorized to request the EIN
Use a paid business database or credit report service
Check prior correspondence from the IRS to the company
Ask the company directly for its FEIN or EIN