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Identify your business or organization 1 federal employer identification number (fein) fein: Web in summary, the registration process is pretty simple! Web filing online is quick and easy! Web proprietorship — the owner (if husband/wife or civil union, enter both individuals’ information) partnership — each general. Click here to go to mytax illinois to file your application online click here to download the pdf form. Identify your business or organization 1 federal employer identification number (fein) fein: