I had been working on the health care website updating my information for the 2017 year. | My son graduated from college in December. He had been on our insurance. We found out he had coverage at his new job so cancelled his coverage 12/28 and paid the premium due. | Now, in March, they went back and billed us an additional $391.33 to cover him for January because we did not put in for a ‘plan change’ until after the 15th of December. | “It was before the coverage started”. Any business would not get away with billing a customer for something they did not want and cancelled before the effective dates.