Marketplace subsidies come in two forms: premium tax credits, which lower your monthly cost, and cost-sharing reductions, which lower your out-of-pocket costs on certain Silver plans.
The amount you qualify for depends on estimated household income for the year — not last year's tax return. If you underestimate income, you may owe money back at tax time. If you overestimate, you may get a refund.
A quick consultation can help you get the estimate right the first time.