Open enrollment for 2027 Affordable Care Act Marketplace coverage began Sunday in most states, opening a sign-up season shaped by higher premiums, narrower insurer participation and new limits on who can receive federal help. The window is one of the year’s most consequential federal policy deadlines because decisions made now determine coverage and household costs for millions of people next year.

The federal enrollment calendar runs through Jan. 15. Consumers must choose a plan by Dec. 15 for coverage to begin Jan. 1; selections made from Dec. 16 through Jan. 15 generally begin Feb. 1. State-run exchanges may use different deadlines, so shoppers should verify dates on their own marketplace.

The central tension is that federal officials say most HealthCare.gov customers will still find heavily subsidized plans, while independent analyses show the underlying cost of benchmark coverage climbing by double digits. The result will vary sharply by income, age, location, family size and the insurers available in each county.

A steeper price test

The Centers for Medicare & Medicaid Services says in its fact sheet that more than 75% of HealthCare.gov customers will have access to a plan costing $50 a month or less after tax credits. CMS also says federal assistance will cover nearly 90% of the lowest-cost plan premium for eligible customers. Those figures describe subsidized prices, not the full premiums charged by insurers.

KFF’s analysis of finalized rates found that the average benchmark silver premium is rising 13% nationally for 2027, including an 11% increase in states using HealthCare.gov and 16% in states operating their own platforms. Its policy review attributes the pressure mainly to higher medical costs, with insurers also citing changes in the risk pool after enhanced pandemic-era tax credits expired. People who receive little or no subsidy will feel the listed-price increases most directly.

Enrollment is already lower

The enhanced premium tax credits ended after 2025, restoring the ACA’s earlier subsidy structure. Marketplace plan selections then fell by 1.2 million for 2026, and paid enrollment stood at about 19.2 million in February, down 12% from a year earlier, according to KFF’s analysis of federal data. The Associated Press separately reported the same decline and said people without subsidies face the greatest affordability pressure.

That history matters because a higher sticker price can influence both family budgets and the insurance pool. If healthier customers leave while people with greater medical needs remain, insurers may face higher average claims. That can add pressure to later premiums, although prices also reflect hospital charges, prescription drugs, labor costs, local competition and regulatory decisions. The 2027 increases cannot be assigned to a single cause.

Eligibility rules are changing

Some lawfully present immigrants will lose eligibility for premium tax credits in 2027 under the 2025 budget law, even though they may still buy full-price Marketplace coverage. The affected categories include some refugees, trafficking victims and asylees; lawful permanent residents and several other listed groups remain eligible. KFF estimates the restriction will increase the uninsured population over time, but the eventual number depends on enrollment decisions and other coverage options.

Federal administrators are also pursuing tighter checks on Marketplace eligibility and annual renewals. A new proposed rule would change verification and redetermination procedures, but it is not final and comments remain open through Nov. 27. Consumers should distinguish proposals from requirements already operating during this enrollment period.

Plan choice requires more than premiums

Eleven insurers had announced exits from at least one state Marketplace for 2027 while seven planned entry into new state markets, according to KFF. The balance does not mean every county loses options, but it raises the likelihood that some customers will see a different menu of plans, networks or drug formularies. Automatic renewal can preserve coverage while still leaving a household in a plan that no longer best fits its doctors, medicines or expected care.

The National Association of Insurance Commissioners advises shoppers to compare premiums with deductibles, copayments, benefits and provider access. Its consumer guide also cautions that health-care sharing ministries, discount programs and risk-sharing arrangements do not carry the same protections as health insurance. A low monthly payment can therefore conceal higher costs when care is needed.

What consumers should verify

Applicants should update projected 2027 household income, review every covered family member, confirm doctors and hospitals in the current directory, and check each regular prescription against the plan formulary. They should also compare total annual costs across metal levels instead of assuming the cheapest premium is the least expensive option overall.

The deadline structure leaves time to compare, but delaying past Dec. 15 can push coverage to February. Medicaid and the Children’s Health Insurance Program accept applications year-round, and qualifying life events can open a special enrollment period after the Marketplace window closes. The immediate policy reality is clear: enrollment is open, but the price and eligibility landscape has shifted enough that passive renewal carries more risk than usual.