How ACA marketplace health insurance works

What is the Health Insurance Marketplace?

The Health Insurance Marketplace is the exchange created by the Affordable Care Act (ACA) where people who do not have job-based or government coverage can shop for and buy private health insurance. The federal version runs at healthcare.gov and covers most states; a minority of states run their own exchange under a different name and web address, but the rules underneath are the same.

Every plan sold on the Marketplace has to be "ACA-compliant": guaranteed issue (no denial or higher price for a pre-existing condition), no annual or lifetime dollar caps on coverage, and a mandatory set of 10 essential health benefits, including hospitalization, prescription drugs, maternity care, and mental health treatment. That baseline is set by ACA Section 1302 and is why a Marketplace plan cannot be a bare-bones policy the way some off-exchange short-term plans can.

What are the metal tiers: Bronze, Silver, Gold, Platinum?

Every Marketplace plan is assigned a metal tier based on its actuarial value, the average share of a standard population's medical costs the plan pays. All four tiers cover the same 10 essential health benefits; the tier only changes how the cost of care is split between you and the insurer, not what is covered.

Source: ACA Section 1302(d) actuarial value tiers, as implemented in CMS's Actuarial Value Calculator methodology (45 CFR 156.135). Plans may vary within 2 percentage points of the listed value.

A Bronze plan's 60% actuarial value means you cover about 40% of an average enrollee's costs through deductibles, copays, and coinsurance, which is why Bronze premiums run cheapest and Platinum premiums run highest: you prepay more, or less, of your expected care through the monthly bill instead of at the pharmacy or the doctor. Many Bronze and some Silver plans on the Marketplace are also high-deductible health plans (HDHPs) that qualify for an HSA; see is an HDHP worth it for the break-even math before you pick one for the deductible alone.

Silver deserves a second look under 250% of the federal poverty line (FPL), because only a Silver plan bought on the Marketplace can trigger cost-sharing reductions (CSR), a separate subsidy that raises the plan's real-world actuarial value, to as high as 94% up to 150% FPL, 87% from 150 to 200% FPL, and 73% from 200 to 250% FPL, at no extra premium. Under 250% FPL, a Silver plan can cover more than an equivalent Gold plan for less money, easy to miss if you shop by premium alone.

How do premium tax credits work?

The premium tax credit (PTC), authorized under Internal Revenue Code Section 36B, caps the share of your income you are expected to spend on the benchmark plan, the second-lowest-cost Silver plan available to you. The government pays the rest, up to the plan's actual premium. What counts as "income" is your household's modified adjusted gross income (MAGI): your adjusted gross income plus any tax-exempt interest, excluded foreign income, and non-taxable Social Security benefits, not your gross paycheck.

The IRS sets an "applicable percentage" of income you are expected to contribute, based on where your MAGI falls as a share of the FPL for your household size. For 2026 coverage, the schedule reverts to the pre-2021 structure Congress originally wrote into the ACA:

Source: IRS Revenue Procedure 2025-25 (Section 36B applicable percentage table for 2026).

2026 marketplace eligibility uses the 2025 federal poverty guidelines, published by HHS in January 2025: 100% FPL is $15,650 for one person and $32,150 for a family of four; 400% FPL is $62,600 for one person and $128,600 for a family of four.

Worked example. A single applicant with a $31,300 MAGI sits at exactly 200% of the 2025 FPL for one person, so their expected contribution is 6.60% of income: $31,300 x 0.066 = $2,065.80 a year, or about $172 a month. If the benchmark Silver plan in their county costs $500 a month (an illustrative figure, not an IRS number, since real benchmark premiums vary by county and age), the premium tax credit covers the difference: $500 minus $172 is a $328-a-month credit. They can apply that same dollar credit to any plan, not just the benchmark, so picking a cheaper Bronze plan can bring the net premium close to zero, while a pricier Gold plan costs more out of pocket even after the credit.

Is the subsidy cliff back in 2026?

Yes, as of this writing. From 2021 through 2025, temporary "enhanced" premium tax credits, passed under the American Rescue Plan Act and extended by the Inflation Reduction Act, removed the 400% FPL cutoff and capped everyone's contribution at 8.5% of income no matter how high their earnings. That enhancement had a built-in sunset of January 1, 2026. A Senate vote on the Lower Health Care Costs Act (S. 3385) to extend it fell short of the 60 votes needed in late 2025, and no other extension has passed as of August 2026.

So the original ACA rule is back for 2026 coverage: the applicable-percentage table above applies, and income even one dollar over 400% FPL gets zero premium tax credit, a hard cutoff rather than a gradual phase-out. This is a live legislative area. If Congress passes a retroactive extension later in 2026, the math here would change; check healthcare.gov's premium tax credit page for the current rule before you rely on it.

Do I have to repay my subsidy if I earn more than expected?

Yes, and the rule got tougher for 2026. The credit paid to your insurer each month, the "advance premium tax credit," is an estimate based on the income you project when you enroll. You reconcile that estimate against your actual MAGI on IRS Form 8962 when you file taxes. If you underestimated your income and got a bigger credit than you actually qualified for, you owe the difference back.

Through tax year 2025, repayment was capped for people under 400% FPL, as low as $375 for a single filer under 200% FPL. Public Law 119-21 eliminates that cap starting with tax year 2026: if your income comes in higher than projected, you now repay the full excess credit, dollar for dollar. If your income is volatile, self-employment being the classic case, update your Marketplace application whenever your estimate changes rather than waiting for tax time.

Who should buy marketplace coverage?

The Marketplace is built for people who fall outside employer-based coverage. Three groups are the clearest fit:

• Self-employed people and independent contractors. With no employer plan to fall back on, the Marketplace, plus the premium tax credit if your income qualifies, is usually the standard path to individual coverage.
• Anyone without an employer plan. Part-time workers, small-business employees whose employer does not offer insurance, and early retirees before Medicare age all shop the same Marketplace as the self-employed.
• People between jobs. Losing job-based coverage opens a Special Enrollment Period (below), and because your income right after a job loss is often lower than it was while employed, you may newly qualify for a much larger credit than you would have gotten while working.

One more case: if your employer's plan is "unaffordable," meaning the self-only premium costs more than 9.96% of household income in 2026 under IRS Revenue Procedure 2025-25, you can decline it and shop the Marketplace for a credit instead. An offer of coverage alone does not disqualify you; an unaffordable offer does not.

When is Open Enrollment, and what is a Special Enrollment Period?

Open Enrollment is the annual window when anyone can sign up for or change Marketplace coverage without a qualifying reason. For coverage starting in 2026, the federal Marketplace's Open Enrollment ran November 1, 2025 through January 15, 2026, with a December 15, 2025 deadline to have coverage start January 1. Some state-run exchanges keep their window open later, some into January or beyond, so check your own state's exchange if it runs one.

Outside that window, you can only enroll or change plans if you qualify for a Special Enrollment Period (SEP), triggered by a qualifying life event: losing job-based coverage, getting married, having or adopting a child, or moving to a new area, among others. Losing job-based coverage, including COBRA running out, qualifies. You generally have 60 days from the date coverage ends (or up to 60 days before a known end date) to enroll, and coverage typically starts the first day of the month after you lose your old plan.

COBRA or the marketplace after losing a job, which wins?

Losing a job is a Special Enrollment Period for the Marketplace and, separately, opens the right to elect COBRA continuation coverage through your old employer's plan. You are choosing between two different trade-offs, not shopping the same product twice.

COBRA keeps your exact plan and network, but at up to 102% of the full premium with no income-based subsidy. A Marketplace plan may use a different network, but it is priced against a premium tax credit, and because post-job income is often lower than your old salary, people who never qualified for a subsidy while employed often do the moment they lose their job. That is why a Marketplace plan is frequently cheaper than COBRA after a layoff, especially once you add the option of a lower metal tier. If you are mid-treatment with a specific provider and continuity matters more than cost, COBRA can still be worth the higher price. Either way, you have 60 days to compare both before the windows close.

The flat truth

The Marketplace is a neutral place to buy ACA-compliant coverage, not a discount itself. The premium tax credit is the actual discount, and for 2026 it is smaller and more of a cliff than it was from 2021 to 2025: nothing above 400% FPL, and full dollar-for-dollar repayment if you guess your income wrong on the low side. If you have no employer plan, self-employed or between jobs, check your MAGI against the FPL table above before you assume marketplace coverage is either a bargain or unaffordable. The number, not the reputation of "Obamacare," decides which one it is for you.