Can my employer cancel my health insurance?

Your employer can cancel you insurance whenever, but with most group plans you are still covered until the end of that month. This is because the plans run monthly and the insurance company has received payment for you by the first of the month. You will probably be eligible for COBRA but the premium will be the amount you and the employer both paid plus 2% and it runs monthly as well (may not be worth it for a doctor bill). Contact your HR department and the insurance company to get exact information.