Plain language
Every term that decides what you pay
Health insurance vocabulary is not hard, it is just deliberately unhelpful. These are the twenty-five terms that actually change the number on your bill, written the way we would explain them on the phone.
Glossary of terms
Showing all 25 terms
A
- Actuarial valueThe share of medical costs a plan pays across a standard population.
Actuarial value is what the metal tiers actually mean. A Silver plan has an actuarial value near 70%, which means that across everyone enrolled in it, the plan covers about 70% of total covered medical costs and enrollees pay about 30% through deductibles, copays and coinsurance. It is a population average, not a promise about your year. A healthy year on a Bronze plan costs you almost nothing; a bad year costs you the maximum out-of-pocket.
C
- Catastrophic planA low-premium, very high-deductible plan for people under 30 or with a hardship exemption.
Catastrophic plans have a deductible equal to the annual out-of-pocket maximum, and cover three primary care visits plus preventive services before that deductible applies. They are available if you are under 30, or at any age with a hardship or affordability exemption. The important catch: premium tax credits cannot be applied to a catastrophic plan, so a subsidised Bronze plan is frequently cheaper.
See alsoBronzeMetal tiers
- CoinsuranceYour percentage share of a bill after the deductible is met.
Where a copay is a flat fee, coinsurance is a percentage. A plan with 20% coinsurance on hospital care means that after your deductible you pay 20% of the negotiated rate and the plan pays 80%, until you hit the out-of-pocket maximum. Coinsurance is where big bills get expensive, which is why the maximum out-of-pocket matters more than the deductible on serious care.
- CopayA flat fee per visit or prescription.
A fixed dollar amount you pay for a specific service, such as $35 for a primary care visit or $15 for a generic prescription. On many plans certain copays apply before you have met your deductible, which is why a Gold plan with $20 office visits can be worth more than its premium difference suggests if you see a doctor regularly.
See alsoCoinsuranceDeductible
- Cost-sharing reductionExtra help with deductibles and copays, Silver plans only, under 250% of the poverty level.
A CSR quietly upgrades a Silver plan to a much richer version of itself. Under 150% of the federal poverty level a Silver plan behaves like a 94% actuarial value plan, better than Platinum, at the Silver premium. Between 150% and 200% you get 87%, and between 200% and 250% you get 73%. CSRs are the single most missed benefit in the marketplace, because they only attach to Silver and people shopping on premium alone buy Bronze.
D
- DeductibleWhat you pay before the plan starts sharing most costs.
The amount you pay out of pocket in a plan year before coinsurance kicks in. Preventive care is covered before the deductible by law, and many plans also cover office visits and generic drugs with a copay before it. A high deductible is not automatically bad: paired with a low premium and a health savings account it can be the cheapest total-cost option for someone who rarely needs care.
E
- Effective dateThe day your coverage actually starts.
Enrolling does not mean you are covered. Coverage begins on the effective date, and only if the first premium is paid. During Open Enrollment, applications completed by December 15 generally take effect January 1, and applications between December 16 and January 15 generally take effect February 1. Special Enrollment effective dates vary by event, and some, such as birth or adoption, are retroactive to the event itself.
- EPONo referrals needed, but no out-of-network coverage.
An Exclusive Provider Organization sits between an HMO and a PPO. You can see any specialist in the network without a referral, but there is no coverage at all outside the network except in a genuine emergency. If your doctors are all in one health system, an EPO is often the best value on the exchange.
F
- Federal poverty levelThe income yardstick every subsidy calculation is measured against.
The FPL is an annual figure published by the Department of Health and Human Services, scaled by household size, with higher schedules for Alaska and Hawaii. Marketplace eligibility is expressed as a percentage of it. Coverage for a given year uses the prior year guidelines, so 2026 coverage is measured against the 2025 numbers. Your percentage of FPL determines both your expected contribution and whether cost-sharing reductions apply.
- FormularyThe list of drugs a plan covers, and what tier each one sits on.
Every plan publishes a formulary organised into tiers, typically generic, preferred brand, non-preferred brand and specialty. The same medication can cost $10 on one plan and $340 on another, and a drug that is not on the formulary at all is your problem entirely. If you take a regular prescription, check the formulary before you compare premiums.
See alsoNetwork
H
- HMOA primary care doctor coordinates your care and issues referrals.
A Health Maintenance Organization requires you to choose a primary care physician who refers you to specialists. Out-of-network care is not covered except in an emergency. HMOs carry the lowest premiums on the exchange because the network is tightly managed, which is a fair trade if your doctors are already inside it.
- HSAA tax-free savings account attached to a qualifying high-deductible plan.
A Health Savings Account is triple tax advantaged: contributions reduce taxable income, growth is untaxed, and withdrawals for medical expenses are untaxed. Only plans specifically designated HSA-eligible qualify, and not every high-deductible plan is. The balance is yours permanently and rolls over, which makes an HSA-eligible Bronze plan a genuinely different financial instrument from an ordinary Bronze plan.
See alsoDeductibleBronze
M
- Maximum out-of-pocketThe hard ceiling on what a covered year can cost you.
The MOOP is the most you can pay for in-network covered essential health benefits in a plan year. Once you reach it the plan pays 100% for the rest of the year. It includes your deductible, copays and coinsurance, but not your premiums, and not anything out of network on an HMO or EPO. When you are comparing plans for a bad year rather than an average one, the MOOP is the number that matters.
See alsoDeductibleCoinsurance
- Metal tiersBronze, Silver, Gold and Platinum, ordered by how much the plan pays.
The tiers describe actuarial value, not quality of care or network size. Bronze covers roughly 60% of costs, Silver 70%, Gold 80%, Platinum 90%. A Bronze and a Platinum plan from the same carrier can share an identical doctor network. Tier tells you how the bill is split, nothing else.
See alsoActuarial valueSilver loading
N
- NetworkThe doctors, hospitals and pharmacies your plan has contracted with.
Networks are county-specific and change every year, sometimes mid-year. A carrier you recognise nationally may have a narrow network in your county. Always verify your specific doctors and your specific hospital, by name, for the specific plan year, rather than trusting the carrier brand.
O
- Open EnrollmentNovember 1 to January 15, the annual window to buy or change a plan.
Outside this window you generally cannot buy marketplace coverage at all without a qualifying life event. Enrolling by December 15 gets you a January 1 start date; enrolling after that generally means February 1. Some state-based marketplaces run longer windows than the federal one, so the date that binds you depends on where you live.
P
- PPOSee any specialist without a referral, and go out of network for more.
A Preferred Provider Organization gives the widest access: no referrals, and partial coverage outside the network. You pay for that flexibility in premium, and out-of-network providers can still balance-bill you for the difference between their charge and what the plan allows. Worth it if you have established specialists spread across systems.
Q
- Qualifying life eventA change that opens a Special Enrollment Period outside the annual window.
Losing other coverage, moving to a new coverage area, marriage, divorce with loss of coverage, birth, adoption, a change in income that alters eligibility, and gaining citizenship or lawful presence all qualify. Most open a 60-day window, and losing coverage uniquely opens a window that starts 60 days before the loss, so you can enrol in advance and avoid a gap.
See alsoSpecial Enrollment Period
R
- ReconciliationSquaring the advanced credit against your actual income at tax time.
Your carrier sends Form 1095-A showing what was advanced on your behalf. You file Form 8962 to compare that against what your actual income entitled you to. Earn less than projected and you get the difference back; earn more and you repay, capped by income band unless you cross 400% of the poverty level, where the cap disappears and the whole amount is owed.
S
- Second-lowest-cost Silver planThe benchmark plan your entire subsidy is calculated from.
The SLCSP is exactly what it sounds like: rank every Silver plan available to you by premium and take the second one. Its premium sets the benchmark. You do not have to buy it, and most people should not, but its price is the anchor for your credit. When a new insurer enters your county and undercuts the benchmark, everyone in that county sees their subsidy fall even though nothing about their own plan changed.
See alsoPremium tax creditSilver loading
- Silver loadingWhy Gold plans are sometimes cheaper than Silver after the credit.
Insurers load the cost of cost-sharing reductions onto Silver premiums specifically, because that is the only tier CSRs attach to. That inflates the benchmark, which inflates everyone subsidy, while Gold premiums stay comparatively untouched. The result is a market where a Gold plan can carry a lower net premium than the Silver plan next to it while covering far more. Always compare after the credit, never before.
See alsoSecond-lowest-cost Silver planCost-sharing reductionMetal tiers
- Special Enrollment PeriodA 60-day window to enrol after a qualifying life event.
An SEP lets you buy or change coverage outside Open Enrollment. Most run 60 days from the event date, and most require documentation such as a termination letter, a lease, a marriage certificate or a birth certificate. Miss the window and you generally wait for the next Open Enrollment, so the date on the paperwork matters more than people expect.
- Subsidy cliffThe point above 400% of the poverty level where the credit stops entirely.
Below the threshold your premium is capped as a share of income. One dollar above it, the credit goes to zero. For an older couple in a high-cost state, crossing that line can cost more than the raise that caused it. Deductible retirement or HSA contributions that reduce modified adjusted gross income are the usual lever for staying under it.
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Knowing the words is not the same as knowing the answer
The definitions above tell you what a deductible is. The estimator tells you which deductible is cheapest for your actual year.