Health insurance, explained simply
Health insurance shares the cost of medical care between you and an insurer, structured around a network of providers, a deductible, and cost-sharing rules that decide who pays what after that. Here's how the main plan types differ, what the ACA marketplace actually offers, typical costs, and the claims process.
1. How health insurance works
Most health plans combine four cost-sharing pieces: a premium (the regular payment to keep coverage active), a deductible (what you pay before the plan starts sharing costs), copays or coinsurance (your share of each visit or service after the deductible), and an out-of-pocket maximum (a yearly cap after which the plan pays 100%).
Plans also organize care through a network — a group of hospitals, doctors, and specialists the insurer has contracted with at negotiated rates. Staying in-network is almost always significantly cheaper than going out-of-network, and some plan types don't cover out-of-network care at all except in emergencies.
2. Main plan types
HMO
- Requires a primary care physician and referrals to see specialists
- Generally the lowest premiums, but the narrowest network
- Little to no coverage for out-of-network, non-emergency care
PPO
- No referrals needed, and out-of-network care is generally covered at a lower reimbursement rate
- More flexibility, usually at a higher premium than an HMO
- Broadest provider access of the common plan types
HDHP
- Lower premium, higher deductible than a typical PPO or HMO
- Pairs with a Health Savings Account (HSA) for tax-advantaged saving toward medical costs
- For 2026, the IRS defines an HDHP as a deductible of at least $1,700 (individual) / $3,400 (family)
EPO
- No referrals needed, similar to a PPO, but no out-of-network coverage at all except emergencies, similar to an HMO
- A middle ground between the two more common plan types
3. The ACA marketplace, in brief
For people who don't get coverage through an employer, the ACA marketplace (Healthcare.gov or a state-run exchange) is the main place to shop for an individual plan. Plans are grouped into metal tiers — Bronze, Silver, Gold, Platinum — that trade off premium against deductible: Bronze plans have the lowest premium and highest deductible, Platinum the reverse.
4. Average costs
Figures below come from aggregated 2026 industry and government analyses (KFF, CMS, Peterson-KFF Health System Tracker). These are averages only — income-based subsidies change the real number dramatically for most marketplace enrollees.
| Scenario | Approximate monthly cost |
|---|---|
| Full price, no subsidy (40-year-old) | ~$497–$625/month |
| After premium tax credit, eligible enrollees (2026 average) | ~$50–$66/month |
Marketplace premiums are rising an estimated 26% on average for 2026, driven in part by enhanced federal subsidies scheduled to expire; roughly 92% of marketplace enrollees receive some subsidy, which softens the effect for most people who qualify.
5. Factors that affect cost
Unlike auto or homeowners insurance, ACA-compliant plans cannot price based on gender or pre-existing health conditions — this is a specific federal consumer protection.
6. Claims & how billing actually works
You receive care
An in-network provider typically bills the insurer directly, rather than you paying the full amount up front.
Insurer processes the claim
The plan applies the negotiated network rate, then your deductible, copay, or coinsurance to determine what you owe.
You receive an EOB
An Explanation of Benefits shows what was billed, what the plan paid, and what you owe — it is not itself a bill.
Provider bills you directly
The remaining balance — your deductible, copay, or coinsurance share — is billed separately by the provider's office.
Some services (certain procedures, out-of-network specialists, non-emergency hospital stays) require prior authorization — approval from the insurer before the service happens — or the claim can be denied even if the service would otherwise be covered.
7. Common myths vs. facts
“An Explanation of Benefits is a bill I need to pay.” ▼
Myth. The EOB's format looks bill-like, which causes confusion.
Fact: An EOB is a summary of how a claim was processed. Any amount you actually owe is billed separately, directly by the provider.
“A plan with a low premium is always the cheapest overall.” ▼
Myth. Premium is only one piece of total cost.
Fact: A low-premium, high-deductible plan can cost more overall in a year with significant medical care, once the deductible and coinsurance are factored in — total cost depends on expected usage, not premium alone.
8. Glossary terms used on this page
HMO
Requires a primary care physician and referrals; narrowest network.
PPO
No referrals needed; broader network at a higher premium.
HDHP
Lower premium, higher deductible; pairs with an HSA.
Copay
A fixed dollar amount owed for a specific service.
Coinsurance
A percentage of costs owed after the deductible is met.
Out-of-Pocket Maximum
The yearly cap after which the plan pays 100%.
Premium Tax Credit
An income-based subsidy that lowers marketplace premiums.
Explanation of Benefits (EOB)
A claim summary, not a bill.