You’re supposed to get one free doctor’s visit every year. So why are so many Americans being charged?

After moving to West Virginia last year, Steve Kuo signed up for a new insurance plan that would cost him $500 a month. But there was one upside: He knew he was entitled to a free preventive visit. He wanted to take advantage of it, so he made an appointment at a clinic near his new home. But then when he got there, they asked about his medical history and he mentioned prior kidney problems. When he received a bill a few weeks later, he had been charged twice for the same appointment: Once as that free preventive visit, once as an “office sick visit” because of the kidney conversation. He was flummoxed — and very annoyed, as he shared on social media. “No copayment means no copayment, exactly as stated in the insurance guidelines,” Kuo told me over email. “What is written and agreed upon should be honored.” He is far from alone. On Reddit, I easily found more than a dozen examples in just the past year of people getting a surprise bill for what they thought was going to be a free visit.  One woman posted a nearly $1,000 bill she’d received for what she thought was going to be a...