A list of the insurers offering worker's compensation insurance is in the Wisconsin Compensation Rating Bureau Annual Report. Click on the "Annual Reports" tab to access the report.
There are about 300 insurance companies licensed to write worker's compensation insurance in Wisconsin. In Wisconsin, all companies writing worker's compensation insurance must be members of the Wisconsin Compensation Rating Bureau (WCRB).

Company Lookup (https://ociaccess.oci.wi.gov/CmpInfo/CmpInfo.oci)
The Company Lookup is a search page that helps locate companies, fraternal benefit societies, associations, town mutual insurers, or rate service organizations licensed or otherwise authorized to transact the business of insurance in Wisconsin. The lookup page also includes company addresses and telephone numbers.

Wisconsin Worker's Compensation Division (www.dwd.state.wi.us/wc/default.htm)
The Worker's Compensation Division is a division of the State of Wisconsin, Department of Workforce Development. The Worker's Compensation Division is responsible for the administration of the Worker's Compensation Act of Wisconsin, Chapter 102 with respect to enforcement, payment of claims, violations, compliance and enforcement of insurance requirements and other related duties.

Madison
Mailing Address
Worker's Compensation Division
P.O. Box 7901
Madison, WI 53707-7901

class="indented"Street Address
201 E. Washington Ave., Room C 100
Madison, WI 53703
(608) 266-1340 Phone
(608) 267-0394 Fax

Milwaukee
State Office Building
Room 330
819 N. 6th St.
Milwaukee, WI 53203
414-227-4381 Phone
414-227-4012 Fax

Appleton
Fidelity Bank Bldg.
Room 310
1500 N. Casaloma Dr.
Appleton, WI 54913-8200
(920) 832-5450 Phone
(920) 832-5355 Fax

Wisconsin Compensation Rating Bureau (WCRB) (https://www.wcrb.org/WCRB/wcrbhome.htm)
(262) 796-4540 Phone
(262) 796-4400 Fax

The Wisconsin Compensation Rating Bureau is a licensed rate service organization for worker's compensation insurance in Wisconsin. The WCRB is responsible for the classification of employers, the rates and rating plans used, all policy forms and analysis of all statistical and other data needed to meet its responsibilities.

Mailing Address
P.O. Box 3080
Milwaukee, WI 53201-3080

Street Address
20700 Swenson Dr., Suite 100
Waukesha, WI 53186