Public vs. Private Health Insurance: Costs, Coverage, and Who Qualifies

The difference between public and private health insurance comes down to who pays and who qualifies. Public plans like Medicare, Medicaid, CHIP, TRICARE, and VA health care are funded by taxpayers and open to people who meet rules set in law — age 65 and older, low income, a disability, military service. Private plans are sold by commercial insurers, paid for mostly through premiums from employers and individuals, and open to anyone who can buy in. As of 2024, about 66% of Americans had private coverage and roughly 36% had public coverage, with some people carrying both at once.¹

What Public Health Insurance Covers and Who Qualifies

Public programs exist to cover people who would otherwise struggle to get insurance on the open market. Eligibility turns on criteria written into federal or state law rather than on your ability to pay a premium.

Medicare covers people 65 and older, along with some younger people who have long-term disabilities, end-stage renal disease, or ALS. It’s funded through a 1.45% payroll tax split between employers and employees, beneficiary premiums, and federal general revenues.²

Medicaid is a joint federal-state program for low-income children, pregnant women, elderly adults, and people with disabilities. The federal share of each state’s spending runs from 50% to 83% depending on per capita income.³ In states that adopted the ACA’s Medicaid expansion, adults earning below 138% of the federal poverty level generally qualify.⁴

CHIP covers children in families that earn too much for Medicaid but can’t afford private coverage, with income thresholds ranging from 170% to 400% of the federal poverty level by state.⁵ Benefits include checkups, immunizations, prescriptions, dental, vision, hospital care, and behavioral health, and total out-of-pocket costs are capped at 5% of a family’s annual income.⁶

TRICARE covers active duty and retired members of the uniformed services, their families, and survivors. Active duty members on TRICARE Prime pay nothing out of pocket; retirees and family members pay enrollment fees and copays.⁷ VA Health Care covers eligible veterans through the Department of Veterans Affairs.⁸

Public coverage has gaps. Original Medicare does not cover routine dental, vision exams for glasses, hearing aids, long-term care, or routine physical exams.⁹ About four in ten Medicare beneficiaries buy supplemental private “Medigap” policies to fill them.¹⁰

How Private Health Insurance Works

Private insurance is sold by commercial companies or offered through self-insured employers, and most privately insured Americans get coverage through a job. In 2024, the average annual premium for employer-sponsored family coverage was $25,572; employers covered about 75% of that cost and workers paid the rest. For single coverage, employers paid about 84%.¹¹ Both the employer and employee shares of premiums are excluded from federal income and payroll taxes, a subsidy the Tax Policy Center estimated cost the federal government $299 billion in 2022.¹²

If you don’t have job-based coverage, you can buy an individual or family plan through the ACA Marketplace or directly from an insurer. Marketplace enrollees with qualifying incomes get premium tax credits paid directly to insurers to lower monthly costs.¹³

Private plans come in several standard shapes. HMOs require a primary care doctor and referrals to see specialists, and generally cover only in-network care, which keeps premiums lower. PPOs let you go out of network at a higher cost and usually skip referrals, with higher premiums. EPOs restrict coverage to in-network providers except in emergencies but typically don’t require referrals. POS plans combine HMO and PPO features. HDHPs pair lower premiums with a high deductible, so you pay more before coverage starts.¹⁴¹⁵

Beyond premiums, you pay deductibles, copayments, and coinsurance. The average annual deductible for single employer coverage was $1,787 in 2024, and deductibles accounted for more than half of all enrollee cost-sharing. On average, employer plans covered 87% of an enrollee’s total health care expenses in 2023.¹¹

What ACA-Compliant Private Plans Must Cover

The Affordable Care Act narrowed some of the historical gap between private and public coverage. All ACA-compliant individual and small-group plans must cover ten categories of essential health benefits, including hospitalization, emergency services, maternity and newborn care, mental health and substance use services, prescription drugs, lab services, preventive care, rehabilitative services, and pediatric services with oral and vision care.¹⁶

Insurers can’t deny coverage or charge higher premiums based on preexisting conditions, health status, or gender. In the individual market, premiums can vary only by age, tobacco use, and family size. Annual and lifetime dollar limits on benefits are prohibited, young adults can stay on a parent’s policy, and minimum medical loss ratios cap the share of premiums that can go to administrative costs and profits.¹⁷

Not every private plan has to meet these standards. Short-term limited-duration plans, fixed indemnity plans, and “grandfathered” plans that predate the ACA are exempt from many requirements, so their benefits and consumer protections can be significantly thinner.¹⁸

Where Public and Private Blur

In practice, a large and growing share of public program enrollees receive their care through private insurance companies working under government contracts.

In Medicare, 55% of eligible beneficiaries — roughly 35 million people — were enrolled in Medicare Advantage plans run by private insurers as of 2026, up from 19% in 2007. The Congressional Budget Office projects that share will reach about 63% by 2034.¹⁹ These plans are funded by Medicare but administered by companies like UnitedHealth Group and Humana, which together account for 46% of all Medicare Advantage enrollment. Medicare Advantage often includes extras Original Medicare doesn’t cover, such as dental, vision, and hearing, and about 75% of enrollees pick a plan with a $0 additional premium.²⁰ The tradeoff: these plans can restrict provider networks and require prior authorization for services, which Original Medicare doesn’t.

Medicaid runs the same way. As of mid-2024, 78% of all Medicaid beneficiaries — more than 66 million people — were enrolled in private managed care organizations rather than getting care directly through the state. Five large publicly traded companies — Centene, UnitedHealth Group, Elevance, Molina, and Aetna/CVS — account for 47% of Medicaid managed care enrollment.²¹ The money is public, the delivery is private.

Finding a Doctor Who Takes Your Insurance

The most consequential practical difference between the two systems is provider access. According to the National Electronic Health Records Survey, 96% of physicians reported accepting new patients with private insurance, compared to 88% for Medicare and 74% for Medicaid.²² State variation is wide: in New Jersey, only about 42% of physicians accepted new Medicaid patients; in North Dakota, 99%.²³

“Secret shopper” studies, where researchers pose as patients calling for appointments, show the gap is wider than physicians self-report. A meta-analysis of 34 such studies found 80% of calls from privately insured simulated patients produced a successful appointment, versus 45% for Medicaid patients. For specialty care, Medicaid callers were 3.3 times less likely to get an appointment than privately insured callers.²⁴ A dermatology study found 96% of callers citing a Blue Cross Blue Shield PPO and 94% of Medicare callers got appointments, compared to just 17% of Medicaid callers.²⁵

Reimbursement rates drive much of this. Medicaid physician fees nationally averaged about 71% of what Medicare pays, with lower ratios for office visits and hospital or emergency department visits.²⁶ Lower payment gives providers a financial reason to limit how many Medicaid patients they take.

What You Actually Pay

Comparing costs is tricky because the two systems are built differently. Public enrollees often pay little or nothing in premiums. Active duty members on TRICARE Prime pay $0 out of pocket. Most Medicare Part A beneficiaries pay no premium if they or a spouse paid payroll taxes long enough. Many Medicaid beneficiaries face minimal cost-sharing. Private insurance enrollees typically carry substantial premium costs even after employer contributions or marketplace subsidies.

In the employer market, total health spending for a family of four — premiums plus out-of-pocket costs — averaged $29,136 in 2024.¹¹ In the ACA marketplace for 2025, the average annual deductible was $2,789, compared to $1,886 for employer plans across all firm sizes.²⁷

Cost problems cut across both systems. A 2023 KFF survey found four in ten insured adults, public and private alike, had delayed medical care because of costs, and more than a quarter said their insurance paid less than expected for a service they thought was covered.¹⁰

Who Has Which Coverage

In 2024, 92% of Americans — about 310 million people — had health insurance for some or all of the year, leaving an uninsured rate of about 8%. Private coverage accounted for 66.1% of the population and public coverage for 35.5%, with overlap because people can carry both.¹ Among people under 65, children were more likely to have public coverage (41.6%) than working-age adults (21.2%), reflecting Medicaid and CHIP’s role with lower-income families.²⁸

Medicare makes coverage near-universal at 65 and older, with less than 1% of that group uninsured.²⁹²⁸

Those numbers may shift. Enhanced ACA premium tax credits enacted in 2021 and extended through 2025 had not been renewed by Congress as of late 2025. The Urban Institute projected that if they expire, 4.8 million more people would become uninsured and 7.3 million would lose subsidized marketplace coverage in 2026, with average out-of-pocket premium costs for marketplace enrollees more than doubling.³⁰ Insurers proposed average gross premium increases of about 18% for 2026, the largest since 2017.³¹

Do You Still Have to Carry Coverage

At the federal level, no. The ACA’s individual mandate penalty was effectively eliminated beginning in 2019, so there is no federal financial consequence for being uninsured. Five jurisdictions — California, Massachusetts, New Jersey, Rhode Island, and the District of Columbia — have their own state-level mandates with tax penalties for residents who don’t maintain qualifying coverage.³²

1
U.S. Census Bureau. Health Insurance Coverage in the United States: 2024
2
Commonwealth Fund. United States Health System Profile
3
National Center for Biotechnology Information. Health Insurance and Access to Care
4
Cover Virginia. Coverage for Adults 19-64 Years Old
5
Medicaid.gov. CHIP Eligibility and Enrollment
6
HealthCare.gov. Children’s Health Insurance Program
7
TRICARE. TRICARE Prime
8
U.S. Census Bureau. Health Insurance Glossary
9
Medicare.gov. What Original Medicare Doesn’t Cover
10
Tulane University School of Public Health and Tropical Medicine. Private vs. Public Health Insurance
11
Peterson-KFF Health System Tracker. How Much Do People With Employer Plans Spend Out of Pocket on Cost Sharing
12
Tax Policy Center. How Does the Tax Exclusion for Employer-Sponsored Health Insurance Work
13
Internal Revenue Service. The Premium Tax Credit – The Basics
14
UnitedHealthcare. Understanding HMO, PPO, EPO, and POS Plans
15
HealthCare.gov. Types of Marketplace Health Insurance Plans
16
Colorado Division of Insurance. ACA Essential Health Benefits
17
Urban Institute. The ACA’s Transformation of Private Health Insurance
18
KFF. Health Policy 101: The Regulation of Private Health Insurance
19
KFF. Medicare Advantage in 2026: Enrollment Update and Key Trends
20
Center on Budget and Policy Priorities. Growth in Medicare Advantage Raises Concerns
21
KFF. 10 Things To Know About Medicaid Managed Care
22
MACPAC. Evaluating the Effects of Medicaid Payment Changes on Access to Physician Services
23
SHADAC. Physician Acceptance of New Medicaid Patients
24
National Center for Biotechnology Information. Medicaid Patients Have Greater Difficulty Scheduling Health Care Appointments Compared With Private Insurance Patients: A Meta-Analysis
25
JAMA Network. Insurance Acceptance, Appointment Wait Time, and Dermatologist Access Across Practice Types in the US
26
Health Affairs. Trends in Medicaid-to-Medicare Physician Fee Ratios
27
Peterson-KFF Health System Tracker. How ACA Marketplace Costs Compare to Employer-Sponsored Health Insurance
28
Centers for Disease Control and Prevention. Health Insurance Coverage
29
KFF. Key Facts About the Uninsured Population
30
Urban Institute. 4.8 Million People Will Lose Coverage in 2026 if Enhanced Premium Tax Credits Expire
31
Center on Budget and Policy Priorities. Five Key Changes to ACA Marketplaces Amid Uncertainty Over Premium Tax Credit
32
KFF. I Heard the ACA’s Individual Mandate Ended – Does It Still Make Sense to Sign Up