Ask your employer. They are required by law to have a Notice To Employees poster displayed somewhere in the workplace, providing you with that information. Also, if you have been injured, and have been unable to earn full wages for five (5) or more days, your employer must report your injury to their insurance company and to the DIA. They are required to give you a copy of this report, which contains the name and address of the insurer. If you have tried to get this information from your employer and failed, the Office of Insurance in Boston can assist you, 617-626-5480 or 617-626-5481.