Health Insurance Glossary: 30+ Terms in Plain English

Health insurance is full of jargon. These are the terms Tennessee residents actually run into, defined the way a navigator would explain them across a desk. For cost rules and enrollment dates, see our costs hub and enrollment calendar.

Advance premium tax credit (APTC)

See Premium tax credit. "Advance" means the credit is paid to your insurer each month, lowering what you owe, instead of arriving at tax time.

BlueCross BlueShield of Tennessee

Tennessee's largest health insurer — the long-standing BlueCross plan covering Tennesseans. It sells marketplace plans, Medicare Advantage (BlueAdvantage), and TennCare managed care (BlueCare). Headquartered in Chattanooga.

Catastrophic plan

A marketplace plan with very low monthly premiums and very high deductibles. Available only to people under 30 or those with a hardship or affordability exemption. Covers three primary-care visits a year before the deductible and all preventive care; otherwise you pay full price until the deductible is met. No premium tax credits on catastrophic plans.

CHIP (Children's Health Insurance Program)

The federal program that funds coverage for kids in families that earn too much for Medicaid but can't afford private insurance. In Tennessee it's called CoverKids — see that entry.

COBRA

A federal law that lets you keep your former employer's group health plan after you leave the job (or certain other events), usually for up to 18 months. You pay the full premium yourself — both your share and the employer's share — plus a small administrative fee, so it's often expensive. See our COBRA and continuation guide.

Coinsurance

Your share of a covered service after you've met your deductible, expressed as a percentage. If your plan pays 80% and you pay 20% for a $1,000 hospital bill, your coinsurance is $200.

Copay (copayment)

A fixed dollar amount you pay for a specific service — for example, $25 for a primary-care visit or $15 for a generic prescription. Copays usually apply whether or not you've met your deductible.

Cost-sharing reduction (CSR)

A discount that lowers your deductible, copays, and out-of-pocket maximum on marketplace plans. Available to households earning roughly 100%–250% of the federal poverty level who enroll in a silver-tier plan. CSRs only work on silver plans — a common gotcha.

CoverKids

Tennessee's CHIP program: free or low-cost coverage for children under 19 (and for pregnant women who don't qualify for TennCare) in households up to 250% of the federal poverty level. No monthly premium; small copays for some services. Enrollment is year-round. See our CoverKids page.

Deductible

The amount you pay out of your own pocket for covered services before your plan starts paying its share. A $3,000 deductible means you pay the first $3,000 of covered care in the plan year. Preventive care and some copay services often don't count toward it.

EPO (Exclusive Provider Organization)

A plan type that pays only for in-network care, like an HMO — but typically doesn't require a primary-care referral to see a specialist. Out-of-network care isn't covered except in emergencies.

Essential health benefits

Ten categories of care that ACA-compliant marketplace plans must cover: outpatient care, emergency services, hospitalization, pregnancy and newborn care, mental health and substance-use treatment, prescription drugs, rehab services, lab work, preventive care, and pediatric services (including dental and vision for kids). Short-term and Farm Bureau plans are not required to cover all of these.

Farm Bureau health plan

Health coverage offered through Tennessee Farm Bureau membership (available in all 95 Tennessee counties; no farming occupation required). These plans are medically underwritten — you can be turned down for health reasons, and pre-existing conditions can face waiting periods. Premiums typically run 30–50% below unsubsidized marketplace plans, making them a real option for healthy buyers who don't qualify for subsidies — and a risky fit for anyone with significant health needs. Enrollment is year-round. See our Farm Bureau health plans page.

Formulary

Your plan's list of covered prescription drugs, usually organized into tiers. Lower tiers cost less out of pocket; higher tiers (often brand-name or specialty drugs) cost more. Always check whether your specific medications are on a plan's formulary before you enroll.

Guaranteed issue

The rule that insurers must offer you coverage regardless of your health history. All ACA marketplace plans are guaranteed issue — they cannot turn you down or charge you more because you're sick. Farm Bureau health plans and short-term plans are not guaranteed issue.

HealthCare.gov (the federal marketplace)

The federal website where Tennesseans shop for, compare, and enroll in ACA marketplace plans. Tennessee uses the federal marketplace rather than running its own state exchange. Enroll online at HealthCare.gov or by phone at 1-800-318-2596 (TTY 1-855-889-4325), 24/7 except holidays. See our marketplace hub.

HMO (Health Maintenance Organization)

A plan type that covers care only from doctors and hospitals in its network (except emergencies). You pick a primary-care doctor, and you usually need a referral from that doctor to see a specialist. HMOs often cost less than PPOs; the trade-off is a narrower network and less flexibility.

In-network / out-of-network

In-network means the doctor, hospital, or pharmacy has a contract with your plan — you pay the lower, negotiated rate. Out-of-network means no contract — your costs are higher, and some plans (HMO, EPO) won't pay for out-of-network care at all. Always check that your doctors are in-network before enrolling.

Medigap (Medicare Supplement)

Private insurance that fills the gaps in Original Medicare — things like the Part A deductible, Part B coinsurance, and the 20% you normally owe on Part B services. In Tennessee, you get a one-time federal 6-month guaranteed-issue window starting when you turn 65 and enroll in Part B; switching later can require medical underwriting. See our Medicare in Tennessee page.

Medicare (Parts A, B, C, D)

The federal health program, primarily for people 65 and older and some younger people with disabilities. Part A covers hospital stays (usually premium-free if you or a spouse paid Medicare taxes long enough). Part B covers doctor visits and outpatient care (monthly premium; $202.90 was the 2026 standard). Part C is Medicare Advantage — Parts A and B delivered through a private plan, often bundled with drug coverage. Part D is standalone prescription-drug coverage. See our Medicare in Tennessee page.

Medicare Advantage (Part C)

Medicare benefits delivered through a private insurer's plan instead of Original Medicare. Most Advantage plans include drug coverage and extras like dental or vision, and they use provider networks. In Tennessee, multiple carriers offer Advantage plans county by county. See our Medicare in Tennessee page.

Medicaid

The joint federal-state program covering low-income children, pregnant women, people with disabilities, and some very-low-income adults. In Tennessee, Medicaid is called TennCare. Tennessee has not expanded Medicaid, so most childless adults don't qualify at any income. See our TennCare page.

Medical underwriting

The practice of reviewing your health history before deciding whether to cover you (and at what price). Farm Bureau health plans and short-term plans use medical underwriting — they can deny you or exclude conditions. ACA marketplace plans cannot.

Metal tiers (Bronze / Silver / Gold / Platinum)

The marketplace's shorthand for how a plan splits costs with you — not a quality rating. Bronze plans pay about 60% of average costs (lowest premiums, highest deductibles). Silver pays about 70% — and it's the only tier that gets cost-sharing reductions. Gold pays about 80%. Platinum pays about 90% (highest premiums, lowest out-of-pocket costs). See marketplace plans compared.

Navigator

A trained, unbiased helper who guides you through marketplace, TennCare, and CoverKids enrollment — for free, with no sales commission. Tennessee's statewide Navigator program is GetCoveredTenn (1-866-475-7879) — funded and operating for the 2027 open enrollment, with in-person help in 10 counties and phone/virtual help statewide.

Network

The group of doctors, hospitals, labs, and pharmacies that have contracts with your health plan. Staying in-network is the single biggest lever you have over what you pay. See our networks guide.

Open enrollment

The annual window when anyone can buy or change a marketplace plan without needing a special reason. For 2027 coverage, it's November 1, 2026 – January 15, 2027. See our open enrollment guide.

Out-of-pocket maximum

The most you'll pay in a plan year for covered in-network care — your deductible, copays, and coinsurance all count toward it. Once you hit it, the plan pays 100% of covered services for the rest of the year. For 2027 marketplace plans, the legal cap is $12,000 for an individual and $24,000 for a family. Premiums don't count toward it.

PPO (Preferred Provider Organization)

A plan type with a network of preferred providers where you pay less, plus the option to go out-of-network and pay more. No primary-care referral is needed to see a specialist. PPOs cost more than HMOs for the extra flexibility.

Premium

What you pay each month to keep your coverage active — whether or not you use any care. Think of it like a subscription fee. Premiums vary by plan, age, tobacco use, and where you live in Tennessee; tax credits can lower them on marketplace plans.

Premium tax credit (APTC)

Money from the federal government that lowers your marketplace premium. The credit is usually applied "in advance" each month (APTC) based on your estimated income. For 2027 coverage, the pre-2021 ACA rules apply: households earning roughly 100%–400% of the federal poverty level qualify, with a hard cutoff at 400% — earn one dollar over and the credit disappears. See our subsidies page.

Prior authorization

Your plan's requirement to approve certain services, procedures, or drugs before you get them. If you skip it, the plan can refuse to pay. Check the plan's rules for things like MRIs, surgeries, and expensive prescriptions — and appeal if authorization is denied. See our prior authorization guide.

Qualifying life event

Something that happens in your life that opens a special enrollment period outside open enrollment — losing other coverage, getting married, having a baby, moving to Tennessee, or aging off a parent's plan at 26, for example. You generally have 60 days from the event to enroll. See our special enrollment guide.

Short-term limited-duration insurance (STLDI)

Temporary coverage meant to bridge gaps — between jobs, waiting for open enrollment, or similar situations. In Tennessee, current market plans can run up to about 364 days initially and up to 36 months total including renewals (federal enforcement of the stricter 2024 rule has been relaxed). These plans are not ACA-compliant: they can deny you for health reasons, exclude pre-existing conditions, skip essential health benefits, and offer no tax credits. See our short-term plans page.

Special enrollment period (SEP)

A 60-day window to enroll in or change a marketplace plan when a qualifying life event happens outside open enrollment. You'll usually need to submit proof of the event. See our special enrollment guide.

TennCare

Tennessee's Medicaid program. Covers children, pregnant women, low-income parents (up to 100% of the federal poverty level), people with disabilities, and some other groups — delivered through three managed-care plans (BlueCare, Wellpoint, UnitedHealthcare Community Plan). Tennessee has not expanded Medicaid, so most childless adults don't qualify. Enrollment is year-round. See our TennCare page.

FAQ

I'm new to all of this. Which terms do I actually need to understand first? Start with premium, deductible, copay, and out-of-pocket maximum — those four determine what you'll actually pay. Then metal tiers and premium tax credit, which determine which plan to pick and what it will cost you. This glossary covers all six above.

What's the difference between a copay and coinsurance? A copay is a flat dollar amount for a specific service ($25 for a doctor visit). Coinsurance is a percentage of the bill you owe after your deductible (20% of a $1,000 bill). Both count toward your out-of-pocket maximum.

Does a higher metal tier mean a better plan? No — metal tiers describe how costs are split, not quality of care. A Bronze plan can be the smart choice if you're healthy and want the lowest premium; a Gold plan can save money overall if you use a lot of care. Run the math for your situation, don't shop by metal color.

What does "underwritten" mean, and why should I care? It means the insurer checks your health history before agreeing to cover you — and can say no or exclude conditions. Farm Bureau health plans and short-term plans are underwritten; marketplace plans are not. That single difference is the main risk of non-ACA plans.

I'm on TennCare. Do premium, deductible, and network mean the same things? Mostly yes — TennCare uses networks and copays like other plans — but costs are much lower (no monthly premium, tiny copays), and the eligibility rules are entirely different. See our TennCare page.

Sources

• Healthcare.gov (federal marketplace; enrollment, metal tiers, plan types)
• CMS 2027 marketplace parameters (out-of-pocket maximums)
• KFF Health News (Tennessee Farm Bureau health plans explainer)
• tn.gov/tenncare and tn.gov/coverkids (TennCare and CoverKids eligibility and benefits)
• GetCoveredTenn (Navigator program details and contact information)
• healthinsurance.org (short-term insurance rules in Tennessee)
• The 2027 plan-year research brief on file at this site (how we verify our facts)