I had a Marketplace plan last year and received advanced premium tax credits. Since the Marketplace already determined that I was eligible for the tax credit, do I still have to file a federal income tax return for the year?

Yes. You are required to file a federal income tax return for any year in which you received advanced premium tax credits. When you file, you will have to calculate how much tax credit you were actually eligible for in that year. The Marketplace determination you received last year was based on your good-faith estimate of what your annual income would be. 

When you file your tax return, you will need two special tax forms: a Form 1095-A and a Form 8962. Once you’ve completed Form 8962, you will know whether you overestimated or underestimated your income. If you underestimated your income when you enrolled, you might have received too much premium tax credit during the year, in which case you might have to repay some or all of the excess amount paid on your behalf. Note that for coverage in 2025, there are limits on how much you will have to repay if your income was less than 400% of the FPL ($62,600 for a household of one or $84,600 for a household of two in 2025). However, starting with coverage in 2026, Marketplace consumers will be expected to repay the full amount of any excess tax credits that are paid on their behalf. If you overestimated your income, you might be owed additional tax credits, which you can take as a tax refund when you file your tax return.