You are correct. Under California law, the employer must pay a minimum of 50% of the employee only premium. However, they are not required to contribute to the additional premium for any dependents that you elect to add to your policy. Perhaps that is what they are referring to when they say you will need to pay 100% of the premium. If they are indeed requiring you to pay 100% of the employee only premium, you can report this to Kaiser as well as the California Department of Insurance. You might also make sure that your employer is aware of this law by providing them a copy of the California insurance code.