Telephone numbers: Illinois Department of Revenue. Department of Employment Security Fax numbers and Local Offices.

Illinois Department of Revenue, including online registration; paper Reg-1, Business registration form; news; publications; forms. If you terminate your business, indicate on your IL-941 and notify the DOR.

Fast Facts for Employers. Illinois Department of Employment Security. Resources for small business, including information about Unemployment Insurance. To report termination of liability for unemployment or other changes in your business, use Form UI-50A.

Booklet IL-700: Illinois Withholding Tax Guide. Handbook for withholding Illinois Income tax. Revised 12/2004.

Starting Your Business in Illinois Handbook. 33-page PDF file.

New hire reporting information.

Workers' Compensation, a comprehensive resource site,including information on Illinois workers compensation.