The Affordable Care Act’s advance premium tax credit (APTC) has been wildly successful. It’s helping millions of Americans pay for health insurance purchased through the individual Marketplace. However, something that’s been confusing for many is the fact that it is an advance. The tax credit is based on the estimated amount that an individual believes they will earn in the coming year. This estimate must be made at the time of the insurance purchase, and, of course, the actual amount earned could ultimately be more or less than anticipated.