What you are paying back is the Premium Tax Credit (PTC) that you received based on your estimate of your income for the year. Yes, you have to pay it back. The amount of PTC that you qualify for is based on your total income for the year. If your income for the year is much higher than the estimate you provided at the beginning of the year, so that you don't qualify for any PTC, then you have to pay back all the PTC that you received. It doesn't matter why your annual income is higher than your original estimate, or that your income was low at the beginning of the year and increased later.
(If your total income for the year is less than 4 times the federal poverty level, there is a cap on the amount that you have to repay. TurboTax will automatically apply the cap if you qualify for it. But if your total income for the year is more than 4 times the federal poverty level you have to repay the full amount.)
