Updated for the 2027 plan year (October 2026). Figures reflect federal HealthCare.gov rules; your state exchange and specific plan may differ.
What is a premium?
A premium is the fixed amount you pay every month to keep your health insurance active — like a subscription. You owe it whether you see a doctor that month or not. If you buy through the Marketplace and qualify for a premium tax credit, the subsidy lowers this monthly bill directly.
Here is the counter-intuitive part: a lower premium usually means you pay more when you actually get care, and a higher premium usually means you pay less at the doctor. The premium is only one of four costs that decide how much a plan really costs you in a year. To see how your income can shrink the premium, read our guide to 2027 subsidies and the premium tax credit.
What is a deductible?
A deductible is the amount you pay out of your own pocket for covered care before your insurance starts paying its share. Say your plan’s deductible is a few thousand dollars: you pay the full bill for non-preventive services until your spending for the year reaches that amount; after that, the plan begins splitting costs with you.
Deductibles reset every January 1. Not everything is subject to the deductible — many plans let you pay a flat copay for a doctor visit or a generic drug even before the deductible is met, and all ACA plans cover preventive care for free from day one. A plan with a low premium almost always carries a high deductible, which is why the premium alone never tells you the full story. You can confirm the official definition at HealthCare.gov’s glossary.
Copay vs. coinsurance
Both a copay and coinsurance are your share of a bill after you meet the deductible — the difference is how they are calculated. A copay is a flat dollar amount (for example, a set fee for each office visit). Coinsurance is a percentage of the bill (for example, 20% of the cost), with the insurer paying the rest.
Copays are predictable and usually apply to routine visits and prescriptions. Coinsurance applies to bigger or variable costs, like surgery, a hospital stay, or imaging, and it kicks in after the deductible. So a plan with “20% coinsurance” means that once your deductible is paid, you pay 20 cents on every dollar of covered care and the plan pays 80 cents — until you reach your out-of-pocket maximum.
The out-of-pocket maximum
The out-of-pocket maximum (OOP max) is the most you will ever pay for covered, in-network care in a single plan year. Once your deductible, copays, and coinsurance add up to that limit, your insurer pays 100% of covered services for the rest of the year. It is the single most important number for protecting you from catastrophic medical debt.
Your monthly premium does not count toward the OOP max, and out-of-network care usually does not either. Every ACA Marketplace plan is legally required to have an out-of-pocket maximum — for the 2027 plan year it can be no higher than $12,000 for an individual or $24,000 for a family (up from $10,600 and $21,200 in 2026), and many plans set theirs lower. That cap is what makes modern coverage a real financial safety net. Think of the deductible as where your sharing begins and the OOP max as where it ends.
Honesty.AI reads any plan in plain English and shows exactly what you’d pay — free and unbiased.
A real cost example: one hospital bill, step by step
The fastest way to understand how health insurance works is to walk one bill through the whole machine. Imagine Maria has a plan with a deductible of a couple thousand dollars, 20% coinsurance, and an out-of-pocket maximum several thousand dollars higher than her deductible. She has an in-network outpatient surgery, and the bill is well above her deductible. Here is exactly who pays what, in order:
| Step | How it is calculated | Maria pays | Insurer pays |
|---|---|---|---|
| 1. Deductible first | Maria pays the bill herself until her deductible is met | 100% of the bill, up to her deductible | Nothing yet |
| 2. Coinsurance on the rest | The rest of the bill is split 20% / 80% | 20% of the rest | 80% of the rest |
| 3. Check the OOP max | Add her deductible and coinsurance together; if the total is still below her cap, the split continues | Never more than her OOP max | Everything above her cap |
| Total for this bill | Deductible + 20% of the remainder | Her deductible plus 20% of the rest | The other 80% of the rest |
So on this first bill Maria pays her full deductible plus 20% of everything after it, and her insurer pays the other 80%. Now suppose she needs another, bigger procedure later the same year. Her deductible is already met, so she goes straight to 20% coinsurance — but only until her total spending for the year reaches her out-of-pocket maximum. Once she hits that cap, her plan pays 100% of every covered in-network service for the rest of the year. That is the safety net doing its job — and the heart of how health insurance works.
What is covered before the deductible (free preventive care)
You do not have to meet your deductible to get preventive care — the Affordable Care Act requires every Marketplace plan to cover a long list of preventive services at no cost to you, even if you have never paid a dollar toward your deductible. There is no copay and no coinsurance when you stay in-network.
Covered-first services include annual wellness checkups, blood-pressure and cholesterol screenings, many cancer screenings (mammograms, colonoscopies), routine immunizations and flu shots, and well-child and well-woman visits. Many plans also apply a flat copay (not the deductible) to everyday primary-care visits and generic drugs. You can see the full federal list at CMS.gov. The catch: a service is only free if coded as preventive — if a screening finds a problem and turns into treatment, normal cost-sharing applies.
Networks and formularies
A network is the group of doctors, hospitals, and pharmacies your plan has contracted with for discounted rates. Staying in-network is how you get the deductible, coinsurance, and OOP-max numbers above. Going out-of-network can mean a much larger bill — or no coverage at all — and that spending usually does not count toward your out-of-pocket maximum.
HMO, PPO, EPO, and POS
Plan types differ mainly in how strict the network is. HMO and EPO plans cover in-network care only (HMOs also require referrals), which keeps premiums lower. PPO and POS plans cost more but offer some out-of-network coverage and more flexibility. For a full comparison, see how to choose a health plan.
What a formulary is
A formulary is your plan’s list of covered prescription drugs, sorted into pricing tiers — generics are cheapest, brand-name and specialty drugs cost more. If your medication is not on the formulary, you may pay the full price, and it may not count toward your deductible or OOP max. Before you enroll, check that your doctors are in-network and your prescriptions are on the formulary.
How to read a health plan in 5 steps
Every plan on the Marketplace shows the same handful of numbers. Read them in this order and you can compare any two plans fairly:
- Find the monthly premium — your fixed cost, and your price after any subsidy.
- Read the deductible — how much you pay before the plan shares costs.
- Check copays and coinsurance — your share for visits, drugs, and procedures.
- Note the out-of-pocket maximum — your worst-case total for the year.
- Confirm the network and formulary — make sure your doctors and drugs are covered.
Add the yearly premium to a realistic estimate of your care costs (capped at the OOP max) and you get each plan’s true annual cost — the only fair way to compare. Learn where these plans are sold in our guide to the health insurance Marketplace.
Putting it all together: how health insurance works
Here is the whole cost-sharing machine in one sentence: you pay a premium every month; when you need care you pay the deductible first, then a copay or coinsurance share, until your spending reaches the out-of-pocket maximum — and in-network care is what keeps every one of those numbers at the level the plan promises.
The trade-off between premium and the rest is the heart of choosing a plan. If you rarely use care, a lower-premium, higher-deductible plan may win. If you have regular prescriptions or expect a procedure, a higher-premium plan with a lower deductible often costs less overall. The good news: for 2027 many Marketplace shoppers still qualify for affordable health insurance after subsidies, even with the enhanced credits gone — so compare every plan before you renew.
Let Honesty.AI do the math for you
Understanding the terms is one thing; comparing dozens of real plans on premium, deductible, coinsurance, OOP max, network, and formulary all at once is another. That is what Honesty.AI does. It is a licensed, unbiased AI insurance assistant that reads every available Marketplace plan, applies your subsidy, and shows your true annual cost on each — with no reason to steer you toward one plan. It works for you 24/7 by chat, voice, or text, and can enroll you in minutes.
See exactly what you’d pay — on every plan
Honesty.AI compares hundreds of plans, applies your subsidy, and shows your real out-of-pocket cost — free, unbiased, and available 24/7.
Frequently asked questions
What is the difference between a deductible and an out-of-pocket maximum?
The deductible is what you pay before your insurer starts sharing costs. The out-of-pocket maximum is the most you will pay all year for covered in-network care — once you hit it, the plan pays 100%. The deductible is where sharing begins; the OOP max is where it ends.
Does my monthly premium count toward my deductible or out-of-pocket maximum?
No. Premiums are separate. Only what you pay for covered care — the deductible, copays, and coinsurance — counts toward your deductible and out-of-pocket maximum.
What is the difference between a copay and coinsurance?
A copay is a flat dollar amount, like a set fee for each office visit. Coinsurance is a percentage of the bill, like 20%, that applies after you meet your deductible. Both count toward your out-of-pocket maximum.
What care is free before I meet my deductible?
Every ACA Marketplace plan covers preventive care — annual checkups, many screenings, and routine vaccines — at no cost when you stay in-network, even before you have paid toward your deductible.
What happens if I go out of network?
You usually pay much more, and that spending typically does not count toward your out-of-pocket maximum. Some plans (HMO, EPO) cover in-network care only, so an out-of-network bill may not be covered at all.
Why is my low-premium plan costing me so much?
Because a low premium almost always comes with a high deductible and coinsurance. You pay less each month but far more when you actually use care. Compare the total yearly cost — premium plus expected care — not the premium alone.
If a word on your plan summary is unfamiliar, our glossary of health insurance terms defines 40 of them in plain English.
Your health insurance deductible is the amount you pay for covered care before your plan starts sharing costs.
Keep learning: How to choose a health plan · The health insurance Marketplace · Affordable health insurance · 2027 subsidies explained
