If you live in a HealthCare.gov state and you don’t update your application, in most cases, HealthCare.gov will automatically adjust the amount of your premium tax credit for next year.  If that turns out to be less than the amount you’re actually eligible for, you will have to pay more premium each month than you otherwise would have had to, although you can receive a refund for the rest when you file your tax return at year end.  On the other hand, if the automatically adjusted premium tax credit amount turns out to be more than you are actually eligible for, you will have to repay all or part of the difference when you file your tax return.