Latest on the Affordable Care Act marketplaces: Will recent enrollment surge be short-lived?

In its final days, the Biden administration tried to cement gains made during the past few years in the uptake of insurance coverage provided through the Affordable Care Act (ACA) marketplaces.

A final rule published Jan. 15 seeks to carry the recent momentum into 2026 via small steps and technical updates such as changes to the ACA risk adjustment model and stricter rules for insurance agents and brokers.

“The Affordable Care Act is more popular than ever,” the Biden administration said in a news release announcing the regulations.

For 2025, a record 24.2 million people enrolled in coverage through the marketplaces, including 3.9 million new enrollees, according to the prior administration. Enrollment doubled from 2021, the year when enhanced subsidies for buying insurance took effect.

At for-profit HCA Healthcare, the nation’s largest health system by hospital and bed count, ACA marketplace volume increased by roughly 45% in 2024, the organization’s leaders said during a Q4 earnings call. The overall enrollment increase in the health system’s markets has been about half as high in 2025 as it was the previous year, but the big question is what will be in store for 2026.

“We see opportunities to work with the Trump administration to find a pathway forward to continue what’s been a very positive community benefit with the exchanges,” said Sam Hazen, HCA’s president and CEO.

However, the status of the recent gains is tenuous because of pending developments in Congress, the executive branch and the Supreme Court.

An ongoing discussion

Republicans in Congress see ACA spending reductions as a way to address the federal deficit while extending tax cuts that have been on the books since 2017.

Retaining the enhanced subsidies for the next 10 years would carry a price tag of $335 billion, according to Congressional Budget Office (CBO) projections. Allowing the subsidies to expire after this year would result in an increase in uninsured of 3.4 million in each year over the next decade.

The view that the subsidies are expendable is not unanimous among the GOP. In an interview published in early January, Sen. Lisa Murkowski (R-Alaska) told a news organization in her home state that she supports extending the premium tax credits (i.e., the enhanced subsidies), saying eliminating them would aggravate the issue of high healthcare costs for consumers.

She also suggested that pressure from Republican constituents could affect the conversation about the subsidies during the FY25 budget reconciliation process. States that could be most affected if the enhanced subsidies expire include the 10 that have not expanded Medicaid as authorized by the ACA. All 10 went for Donald Trump in the 2024 election. (The list of the most impacted states will expand considerably if the federal medical assistance percentage for the Medicaid expansion population is slashed, as has been put forth in preliminary budgetary discussions.)

Republicans could find savings related to the subsidies, which began in 2021 and are on the books through 2025, while still extending them. The GOP is considering technical changes that, in combination, would create projected savings of close to $100 billion over a decade.

Examples include removing a cap on repayment amounts of excess subsidy payments made to low-income recipients and repealing a 2022 provision that negated the ACA’s family glitch.

The administration’s outlook

The ACA was not a prominent topic during last week’s confirmation hearings of Robert F. Kennedy Jr., the nominee to serve as HHS secretary in the Trump administration. Questions from senators tended to focus on issues that have been more closely linked to Kennedy, such as his stated intent to address the underlying causes of chronic disease, or his past positions on vaccines.

The administration theoretically could weaken ACA provisions that prohibit insurers from denying coverage based on preexisting conditions, for example, or establishing annual or lifetime coverage caps. Such steps would come via regulations relaxing enforcement against health plans that do not adhere to the requirements. Illustrating a different approach, Vice President J.D. Vance said in September it may be advantageous to slot people with preexisting conditions into a separate risk pool as part of what he called a “deregulatory agenda” to allow for more consumer choice.

Another possibility would be to reinstate steps taken during Trump’s first term to curtail spending on outreach and assistance for prospective marketplace enrollees. Funding for the ACA navigator program was limited to $10 million in 2020 before increasing to $162 million (including the state-run marketplaces) in 2022.

Kennedy pledged to adhere to the law in setting such policies and said he would strive to make available “affordable, accessible, high-quality health insurance coverage that best meets the needs of individuals and their families.”

He declined to criticize short-term, limited-duration plans, which the prior Trump administration expanded through regulations to create an alternative in the individual-insurance market. The Biden administration restricted the availability of the plans, saying they lack the required protections of ACA plans and thus can leave enrollees in a bind if a serious health situation arises.

Litigation nears a climax

The Supreme Court also stands to affect the viability of ACA marketplace insurance, with implications for group health plans as well. The court last month agreed to hear arguments in the Braidwood v. Becerra case, which is about the ACA’s mandate that most private health plans offer coverage with no cost sharing for designated preventive services.

Plaintiffs in the case won a 2023 ruling in a Texas federal court, which overturned the mandate for health plans to fully cover preventive services recommended since March 2010 by the U.S. Preventive Services Task Force (USPSTF), on the basis that USPSTF members were not constitutionally appointed. Last year, the U.S. Court of Appeals for the Fifth Circuit upheld the ruling but reduced the impact by saying the mandate should be lifted only for the plaintiffs.

The Biden administration’s Department of Justice (DOJ) appealed to the Supreme Court, hoping to establish that USPSTF members were legally appointed. It’s unclear how vigorously the Trump administration’s DOJ will argue the case. If the administration takes a pass, another entity such as a state government could petition to step in.

The plaintiffs hoped the Supreme Court would expand its consideration of the case to include the mandates for full coverage of services recommended by the Health Resources and Services Administration for women and for children, along with the CDC’s Advisory Committee on Immunization Practices. Although the Supreme Court declined to hear those arguments in the current case, the issue is still being contemplated by the district court, meaning it eventually could be elevated to the high court.