Health insurance enrollment through the Affordable Care Act marketplaces could drop by as many as 5 million people this year if federal premium subsidies lapse, according to a new analysis from KFF. The estimate points to a likely surge in monthly costs for millions of enrollees, with the biggest impact expected in states where marketplace coverage has become heavily dependent on enhanced tax credits.
Why the market is vulnerable
The ACA marketplaces were designed to give people who do not get coverage through an employer access to private insurance plans, often with federal financial help. Since Congress expanded premium subsidies in 2021, many households have paid far less for coverage than they would have under the original law.
Those enhanced subsidies have been central to the marketplace’s recent growth. CMS said 21.4 million people selected plans during the 2024 open enrollment period, the highest level since the exchanges opened. KFF says that momentum could reverse quickly if the extra aid expires and premiums jump for current enrollees.
What the analysis found
KFF’s estimate assumes that a lapse in the federal subsidy expansion would raise out-of-pocket premium costs enough to push many healthy and lower-income consumers out of the market. The group projects enrollment could fall by about 5 million people, a decline that would erase a large share of the gains the marketplaces have posted in recent years.
The expected drop is not only about price sensitivity. It also reflects the way ACA enrollment works. Many consumers decide each year whether to renew, switch plans or drop coverage based on expected monthly costs, and even modest increases can change those choices. When premiums rise, healthier enrollees are typically more likely to leave first, weakening the overall risk pool.
Premium shock could reshape the risk pool
Analysts and industry groups have long warned that subsidy cuts can trigger a feedback loop: as healthier people exit, average medical costs rise for the remaining pool, which can push premiums higher. That effect matters because marketplace pricing is built around broad participation across age and health categories.
In practical terms, the people most exposed are those who buy insurance on their own, especially middle-income households that have benefited from the enhanced subsidies. The Commonwealth Fund and KFF have both found that improved affordability has been a major reason enrollment climbed after the subsidy expansion took effect.
If those credits disappear, some consumers may still qualify for standard ACA aid, but the amount would be smaller. Others, particularly people just above eligibility thresholds, could face large premium increases and choose to go uninsured instead.
Policy stakes for lawmakers
The subsidy issue has become a political and budgetary fault line. Supporters argue that extending the enhanced credits would preserve coverage gains and prevent premium spikes. Opponents say the expanded subsidies are expensive and should not be made permanent without broader reform.
The Congressional Budget Office has previously estimated that premium assistance affects enrollment substantially because marketplace consumers respond quickly to changes in net cost. That makes the issue unusually sensitive to legislative timing. If lawmakers do not act before the current subsidies lapse, insurers, brokers and state marketplaces may have to prepare for a rapid reset in consumer demand.
What it means for consumers and the industry
For readers, the key takeaway is straightforward: the cost of ACA coverage could rise sharply, and so could the risk of losing it. That would affect families renewing coverage, people shopping for the first time and small business workers who rely on individual plans.
For the insurance industry, a 5 million-person decline would mean a smaller and potentially less balanced marketplace. Fewer enrollees can reduce competition, weaken insurer participation and complicate rate setting for the following year.
The next developments to watch are whether Congress extends the subsidies, how insurers revise their 2026 filings, and whether marketplace enrollment begins to slip ahead of the next open enrollment period. Those decisions will determine whether the ACA market continues its recent growth or enters a period of retrenchment.
