How has enrollment in ACA marketplaces changed since ARP?
Executive summary
Enrollment in the ACA Marketplaces rose sharply after the American Rescue Plan (ARP) enhancements: record-high signups reached about 24.2 million for plan year 2025, up from roughly 21.3 million in 2024 [1]. Analysts attribute that surge to ARP/IRA subsidy boosts and related enrollment flexibilities; several policy changes scheduled for late‑2025 and 2026 threaten to reverse some of that growth [2] [3].
1. Rapid growth tied directly to ARP subsidy enhancements
The ARP (and its extension in the Inflation Reduction Act) expanded subsidy eligibility above 400% of the federal poverty level and reduced required household contributions, which substantially increased affordability and helped swell enrollment from roughly 11.4 million in 2020 to over 21 million by 2024 and to about 24.2 million in 2025 [3] [1]. Healthinsurance.org and other analysts credit the enhanced premium tax credits for driving the “record‑high” 2025 enrollment numbers [2] [4].
2. Specific mechanics: who benefited and how much
Under ARP/IRA rules people at lower incomes could face $0 premiums for benchmark Silver plans (income up to 150% FPL), and households up to and above 400% FPL saw bigger subsidies than before ARP because the applicable percentage of income required for premiums was lowered (for 2025 people paid between 0% and 8.5% of income for the benchmark Silver plan) [5] [3]. The result: larger subsidies across income levels and expanded eligibility produced measurable increases in enrollment [3].
3. Policy changes and timing that could reduce enrollment
Multiple federal rule changes and congressional actions in 2025 create downward pressure on Marketplace rolls. The final 2025 Marketplace rule included provisions — some later stayed or challenged in court — that CMS estimated could reduce enrollment by 750,000 to 1.8 million after the 2025 peak [6] [7]. Separately, the ARP/IRA subsidy enhancements are scheduled to sunset at the end of 2025 unless Congress extends them; analyses warn that reverting to pre‑ARP rules would shrink subsidies and likely reduce enrollment [5] [3].
4. Immediate effects already visible in open enrollment 2025/2026
Open enrollment dynamics changed in 2025: Healthinsurance.org and other organizations noted that expanded eligibility (including DACA recipients under a new rule) and continued ARP subsidies for 2025 helped draw newcomers in the lead‑up to the 2025 open enrollment period, contributing to the 24.2 million signups figure [4] [1]. But new final‑rule provisions effective August 25, 2025 and congressional votes in late 2025 altered the landscape for 2026 coverage, raising premiums and risking coverage losses if subsidy enhancements are not extended [7] [2].
5. How big the hit could be if enhancements lapse
Analysts project substantial enrollment declines if the enhanced credits end. One piece cites Congressional Budget Office modeling that Marketplace enrollment could fall from 22.8 million in 2025 to 18.9 million in 2026 without the ARP enhancements [8]. The Conference Board and CMS rule analyses similarly expect enrollment drops in the high hundreds of thousands to low millions if recent regulatory changes and subsidy expirations proceed [6] [3].
6. Winners and losers: distributional consequences
The coming reversion would disproportionately affect middle‑income and older enrollees. Households above 400% FPL would lose subsidy eligibility entirely under pre‑ARP rules; older enrollees pay more due to age‑rated premiums, so the loss of subsidies hits them harder [5] [9]. Lower‑income enrollees who benefited from $0 benchmark premiums (up to 150% FPL) also stand to lose substantial savings if lawmakers don’t extend the enhanced credits [5] [10].
7. Competing narratives and political context
Sources present competing framings: advocates and analysts portray ARP/IRA expansions as the primary driver of the enrollment surge and warn that ending them will cause mass losses and “sticker shock” [2] [11]. Regulators and some policymakers argue that recent marketplace integrity rules are designed to curb improper enrollments and reduce costs, and CMS projected these rules could lower enrollment as a tradeoff [7] [6]. The Conference Board flags fiscal tradeoffs from a permanent extension versus temporary fixes [3].
8. Limits of available reporting
Available sources document enrollment totals through early 2025 and model scenario impacts of sunsetting subsidies and regulatory changes; they do not provide final, comprehensive effectuated enrollment figures for late‑2025/2026 or consumer‑level longitudinal churn after the policy shifts — those outcomes are not found in current reporting [1] [7]. Policymakers’ ultimate choices in December 2025 and legal outcomes around the 2025 rule will determine the real enrollment trajectory [5] [7].
Bottom line: ARP/IRA subsidy enhancements drove record Marketplace enrollment — roughly 24.2 million in 2025 — and analysts uniformly warn that ending those enhancements or implementing stricter enrollment rules will cut enrollment by hundreds of thousands to millions unless Congress or the courts change course [1] [6] [3].