The opening of the health insurance marketplaces under the Affordable Care Act (ACA) on Jan.1 means you must be vigilant in your dealings with the health insurance companies. Or you could face major problems. For example, do your existing contracts with insurers mean you’re already included in an exchange network? And, it’s possible you’ll have to refund payments to an insurer if a patient who bought coverage in the ACA marketplace doesn’t pay his or her premiums. – See more