Medicare Glossary
Medicare has its own language — and the official definitions often create more confusion than they resolve. This glossary is written from a data analyst's perspective: we've analyzed every Medicare Advantage and Part D plan in the CMS database across 35,000+ U.S. locations, and these definitions reflect what each term actually means when you're comparing plans and making enrollment decisions. Jump to any letter below or Ctrl+F to find what you need.
The most common hospital type in the U.S. — a general-purpose facility equipped to handle a wide range of medical conditions, surgeries, and emergencies. When CMS publishes hospital data, roughly 70% of the 4,500+ Medicare-certified hospitals are classified as acute care. Why this matters for Medicare: acute care hospitals are the facilities most people think of when they say "hospital" — they have emergency departments, operating rooms, intensive care units, and multi-specialty medical staffs. If you're choosing a Medicare Advantage plan, the acute care hospitals in your plan's network are the facilities you'll use for most inpatient and emergency care. Because they handle the broadest range of conditions, their CMS star ratings reflect performance across all five quality domains: mortality, safety, readmission, patient experience, and timely care.
See also: Critical Access Hospital, CCN
October 15 – December 7. This is the single most important window for Medicare beneficiaries. Why it matters from a data perspective: insurers update premiums, formularies, and provider networks every plan year, so even if your plan name stays the same, the underlying cost structure may shift significantly. In our analysis, we routinely see plans that were competitive in one year become mid-pack or worse the next — the only way to catch that is to re-compare during AEP.
Data point: Across our 7,800+ plan dataset, average Part C premiums shift 5–15% year-over-year for many plans. A $0-premium plan this year could charge $25/month next year — that's $300 you'd miss if you don't re-check.
Your formal right to challenge a coverage denial — and a step most people don't know they can take. If a plan says a drug isn't covered or denies a claim, you (or your doctor) can file an appeal requesting reconsideration. What the official definition doesn't tell you: appeals succeed more often than people expect, particularly for formulary exceptions where a doctor provides clinical justification. The process has defined timelines (72 hours for expedited, 7 days for standard Part D), and you can escalate to an independent review if the plan still says no.
A billing agreement where a provider accepts the Medicare-approved amount as full payment — meaning they can't bill you for the difference (called "balance billing"). This matters most in Original Medicare, where there are no network restrictions and providers can choose whether to accept assignment. Practical impact: if you're on Original Medicare without Medigap, seeing a provider who doesn't accept assignment can result in charges up to 15% above the Medicare-approved rate. In Medicare Advantage, network contracts effectively handle this, so assignment is less of a factor.
Anyone enrolled in Medicare — roughly 67 million Americans as of 2025. You'll see this term in CMS documents, plan literature, and quality reports. When we say "beneficiary," we mean someone with active Medicare coverage of any type (Original Medicare, MA, or both). CMS publishes all of its plan quality and enrollment data at the beneficiary level, which is what powers the comparisons on this site.
An Original Medicare concept that catches people off guard. A benefit period begins when you're admitted to a hospital and ends after 60 consecutive days without inpatient care. Why it matters: each new benefit period resets your Part A deductible (~$1,632 in 2024). If you're discharged, readmitted 61 days later, you pay that deductible again. This is one of the structural cost risks of Original Medicare that Medicare Advantage plans eliminate — MA plans use annual deductibles and MOOP instead of this rolling benefit-period model.
A 6-character identifier CMS assigns to every Medicare-certified facility. Think of it as a hospital's Social Security number — it's the primary key that links hospital quality data, cost reports, and survey results across every CMS database. When we build hospital profiles, the CCN is how we join star ratings, infection data, HCAHPS scores, and readmission rates into a single view.
The federal agency that administers Medicare and publishes the data we analyze. CMS certifies every MA and Part D plan, assigns Star Ratings, enforces marketing rules, and releases the plan-level datasets (premiums, formularies, benefits, quality scores) that make independent comparison possible. All data on this site comes from CMS sources — we don't generate our own ratings or accept data from insurers. When we say "CMS data," we mean the same datasets that power Medicare.gov — we just organize them differently.
A percentage-based cost share — you pay X% of a service, the plan pays the rest. Coinsurance creates unpredictable costs because your bill depends on the total charge. A 20% coinsurance on a $200 office visit is $40, but 20% on a $5,000 outpatient procedure is $1,000. Comparison tip: when evaluating plans, look at whether services use coinsurance or copays. Plans that use copays (fixed dollar amounts) for common services are more predictable in your budgeting.
See also: Copay, Deductible
A fixed dollar amount you pay per service — $20 for a primary care visit, $40 for a specialist, $10 for a Tier 1 drug. Unlike coinsurance (a percentage), copays give you cost certainty. What the data shows: most Medicare Advantage plans use copays for routine services, which makes budgeting easier. But watch the specialist and emergency copays — across plans we analyze, specialist copays range from $0 to $50+ for the same visit type. That variance can add up quickly if you see specialists regularly.
The most misunderstood phase of Part D coverage. After you and your plan have spent a combined ~$5,030 on drugs, you enter the coverage gap. Historically, this was a financial cliff — you paid nearly full price. The Inflation Reduction Act fundamentally changed this: starting in 2025, your total out-of-pocket drug costs are capped at $2,000/year. Once you hit that cap, you pay $0 for the rest of the year. Practical impact: the donut hole still exists structurally, but the $2,000 hard cap means it now has a defined bottom. This makes high-cost specialty drugs far more affordable than they were pre-2025. It also means the gap between Part D plans narrows for people with expensive prescriptions — the cap is the same regardless of which plan you choose.
See also: Catastrophic Coverage
Existing drug coverage that's "at least as good as" standard Part D — typically from an employer, union, VA, or TRICARE. Why this matters: if you have creditable coverage, you can delay Part D enrollment without triggering the late enrollment penalty. The trap: your employer is required to send you a "creditable coverage notice" each year. Keep that letter. When you eventually join Part D, that document is your proof. Without it, CMS assumes the worst and applies the penalty retroactively. We've seen this catch people years later.
The final phase of Part D drug coverage — and since 2025, the one with the clearest rule: once your out-of-pocket drug spending hits $2,000 in a calendar year, you pay $0 for covered drugs for the rest of the year. This cap is identical across all Part D plans. Why this changed everything: before the Inflation Reduction Act, catastrophic coverage still required 5% coinsurance — meaning a $10,000/month specialty drug still cost $500/month even after reaching catastrophic phase. The $2,000 hard cap eliminated that open-ended risk entirely.
A Medicare Advantage plan restricted to people with qualifying chronic conditions — diabetes, heart failure, ESRD, chronic lung disorders, and others. C-SNPs aren't just regular MA plans with a label; they're required to provide condition-specific care coordination, tailored benefits, and specialized provider networks. Data insight: C-SNPs tend to have lower premiums than comparable general-enrollment plans because CMS provides higher risk-adjusted payments for their populations. If you qualify, they're worth evaluating — the care coordination alone can reduce hospitalizations.
The most common type of Dual-Eligible Special Needs Plan — and the one most members are in without realizing it. The Medicare side and the Medicaid side stay separate in every operational way that matters: different ID cards, different customer-service phone lines, different doctor lookups, different appeals processes. CMS does require the D-SNP issuer to coordinate with the state Medicaid agency on benefits and care management — but coordination is a much weaker promise than integration. The tell: if you have a question and the customer-service rep says "for that, you'll need to call Medicaid," you're in a Coordination-Only plan. Why most D-SNPs are this kind: deeper integration (HIDE or FIDE) requires the state Medicaid agency to contract with the same carrier that's running the D-SNP — operationally hard work that most states haven't done. So Coordination-Only is the default, not the exception. It isn't a bad plan; it's just the most common kind. If your state offers a HIDE or FIDE alternative, the integrated plan usually means one card, one phone number, and one team that knows about both halves of your coverage.
What this looks like in practice: you're at the pharmacy and a covered drug suddenly costs $40 instead of $0. With a Coordination-Only plan, you call the D-SNP first; if they say "we covered our part — Medicaid was supposed to cover the rest," you then call Medicaid to find out why they didn't. With a FIDE plan, that's one phone call, not two.
A small, rural hospital (25 or fewer inpatient beds) that receives special cost-based reimbursement from Medicare to keep essential services in underserved areas. CAH designation was created because standard Medicare payment rates don't cover the higher per-patient costs of running a low-volume hospital — without the subsidy, many rural facilities would close. What this means for patients: Critical Access Hospitals are often the only hospital within 35+ miles in rural communities. They typically have emergency departments and can stabilize patients, but may transfer complex cases to larger acute care facilities. In our hospital data, CAHs often show as "Not Rated" by CMS because the star rating methodology requires minimum case volumes that many small hospitals don't meet — so the absence of a rating doesn't necessarily indicate poor quality. If you live in a rural area, your nearest CAH is likely your primary emergency option regardless of network status (Medicare covers emergency care at any hospital).
Data point: There are approximately 1,350 Critical Access Hospitals in the U.S., concentrated in the Great Plains, Appalachia, and the rural West. Many serve as the sole healthcare anchor for their communities.
See also: Acute Care Hospital, CCN
The annual amount you pay before the plan starts covering costs. For Part D, the maximum deductible is $590 (2026) — but many Part D plans set it at $0, and the range across plans in a single zip code can vary widely. Analysis tip: a plan with a $0 deductible and a $15/month premium costs $180/year in premiums. A plan with a $0 premium but a $590 deductible costs $590 before coverage kicks in. The "cheapest" plan depends on your actual drug usage — not the premium alone. Medicare Advantage plans may have separate medical and drug deductibles; always check both.
MA plans exclusively for people who have both Medicare and Medicaid. D-SNPs are the most common type of SNP in our dataset — they account for roughly a third of all SNP enrollments nationally. Why they stand out in the data: D-SNPs almost universally have $0 premiums, $0 deductibles, and very low copays because they're designed for low-income populations who are already receiving state Medicaid assistance. They also coordinate benefits between the two programs, which reduces the administrative burden on members. If you're dual-eligible and not in a D-SNP, you may be leaving significant benefits on the table.
See also: C-SNP, SNP, Coordination-Only D-SNP, HIDE, FIDE
See Dual Eligible Special Needs Plan. The unhyphenated spelling shows up most often in plan marketing materials; CMS's official term uses the hyphen ("D-SNP"). Same plan type either way.
The cost classification assigned to each drug on a plan's formulary — and one of the most impactful variables when comparing Part D plans. Most plans use 5 tiers: Tier 1 (preferred generic, typically $0–$5), Tier 2 (generic, $5–$20), Tier 3 (preferred brand, $30–$50), Tier 4 (non-preferred, percentage-based), Tier 5 (specialty, $50–$100+). The critical insight: the same medication can sit on Tier 2 in one plan and Tier 4 in another — a difference that can cost hundreds of dollars per year. This is why checking the formulary for your specific drugs is the single most important step in choosing a Part D plan.
See also: Formulary
The legal contract between you and your Medicare Advantage or Part D plan — and the document that wins every argument. Each fall, before the new plan year starts, your plan mails you a 100-to-200-page EOC that spells out exactly what's covered, what you pay, what's excluded, and the rules you have to follow. The Summary of Benefits (the 5-to-15-page glossy version your plan also sends) is marketing; it skips the fine print on purpose. The EOC has the fine print. The rule that matters: if a customer-service rep tells you something different from what the EOC says, the EOC wins. Every time. Verbal answers don't override the contract. Practical advice: when a benefit matters to you — a specific surgery, a specialty drug, hearing aids, transportation rides, the rules around emergency out-of-network care — search the EOC for that exact phrase before you enroll. Most plans publish the current EOC on their member portal as a searchable PDF. You don't have to read all 200 pages; you just have to find the section that covers your situation.
Real-world scenario: a member calls their plan to ask whether cataract surgery at a specific outpatient surgery center is covered. The phone rep says "yes, it's covered." Three months later, a $4,200 bill arrives because the surgery center wasn't in network — and the EOC clearly required prior authorization for out-of-network outpatient surgery. The phone rep was wrong. The EOC was the contract. This kind of dispute happens often enough that plans now record the calls — but the EOC is still what you can cite.
See also: Formulary
A document your plan sends after every healthcare service — showing what was billed, what the plan paid, and what you owe. It's not a bill (that comes separately), but it's your best tool for catching errors. Practical advice: review every EOB. If the "amount you owe" looks wrong, compare it against your plan's Summary of Benefits to verify the copay or coinsurance matches. Billing mistakes happen, and the EOB is your audit trail. Keep them for at least a year — they're also useful for tracking your progress toward your plan's MOOP.
A federal program that can eliminate most Part D drug costs for people with limited income. Income thresholds: roughly ~$22,590 (individual) or ~$30,660 (couple) in 2025. What the data shows: Extra Help is significantly underutilized — millions of beneficiaries who qualify haven't applied. If you qualify, copays drop to $0–$11.20 per prescription, deductibles disappear, and premium assistance covers most or all of your Part D premium. Qualifying also triggers a Special Enrollment Period, letting you switch plans outside of AEP. Apply through Social Security.
See also: LIS
The deepest level of D-SNP integration — and frankly, the closest thing to a "one and done" experience that exists in dual-eligible coverage. The same insurance company runs both your Medicare Advantage plan and your Medicaid managed-care plan, combining them into a single plan ID, a single member card, a single customer-service line, and a unified benefit package. Why this matters in practice: when something goes wrong with a covered service, you don't get bounced between Medicare and Medicaid — there's only one entity, and they own the answer end-to-end. The catch: FIDE plans require the state Medicaid agency to contract with the same carrier that runs the D-SNP, which is operationally hard, and only a minority of states have built FIDE programs. If you live in a FIDE-available state, look closely — the lower paperwork burden alone is usually worth it for a full-benefit dual-eligible. If you don't, your most-integrated option is probably a HIDE.
Structural difference, in plain terms: a Coordination-Only D-SNP gives you two cards, two phone numbers, two appeals processes. A FIDE plan gives you one card, one phone number, one appeals process. For a dual-eligible juggling chronic care, prescriptions, and (sometimes) home- and community-based services, that simplification is the single biggest benefit FIDE delivers. The premium and copays are usually identical; the difference is who you have to call when something needs fixing.
See also: D-SNP, HIDE, Coordination-Only D-SNP
A plan's official list of covered drugs, organized by cost tier — and arguably the single most important document when choosing a Part D plan. Every plan has its own formulary, and they differ substantially. What we see in the data: a common medication like atorvastatin (generic Lipitor) might be Tier 1 ($0 copay) on one plan and Tier 2 ($15 copay) on another in the same zip code. For specialty drugs, the variance is even wider — some plans cover a biologic that others exclude entirely. Formularies can also change mid-year (with CMS-required notice), and they always change at annual renewal. Bottom line: never choose a Part D plan based on premium alone. Check the formulary for every drug you take, note the tier, and look for prior authorization or step therapy restrictions.
See also: Drug Tier, Prior Authorization
A time-limited window during which a Dual-Eligible Special Needs Plan keeps covering you after your state Medicaid eligibility ends — buying you time to requalify before you lose the plan entirely. CMS requires every D-SNP to offer at least a 1-month grace period; many plans extend it up to 6 months, and the exact length is set in the plan's Evidence of Coverage. The reason this term exists: the #1 cause of dual-eligibles losing D-SNP coverage isn't anything to do with Medicare — it's a missed Medicaid renewal. Your state Medicaid agency mails a renewal packet roughly every 12 months. If it goes to an old address, gets buried in junk mail, or just doesn't get returned in time, your Medicaid lapses. You don't always find out until your D-SNP gets denied at the pharmacy counter or a bill arrives that you weren't expecting. What the grace period does: CMS makes the D-SNP keep covering you while you scramble to get re-enrolled in Medicaid. If you can't requalify by the end of the grace period, you're moved out of the D-SNP and into a Special Enrollment Period to pick a standard Medicare Advantage plan — but you've now lost the dual benefits. Best advice: when your D-SNP welcome packet arrives, find the section on Medicaid renewals. Set a calendar reminder for your state's renewal month. The 30 minutes you spend updating your address with the state Medicaid agency and returning the form is the cheapest insurance against losing thousands of dollars in Medicare coverage. If you've moved recently, update your address with both Medicare and the state — they don't always share that information.
See also: D-SNP, Special Enrollment Period, Evidence of Coverage
The standardized code list Medicare uses to identify every billable procedure, service, supply, and drug. Think of it as a barcode for healthcare — every office visit, every imaging study, every wheelchair, every chemotherapy infusion has a number. HCPCS is split into two levels: Level I covers most clinical services (these are CPT codes maintained by the American Medical Association — office visits, surgeries, lab work) and Level II covers ambulance trips, durable medical equipment, prosthetics, and clinic-administered drugs. Why we use HCPCS in our analysis: when we show "what this doctor does" on a doctor profile, the underlying numbers come from the public CMS Provider Utilization & Payment file, which is keyed on HCPCS. We translate the codes into plain-English procedure names so they're readable, but every row maps back to a specific code that can be audited against the source CMS dataset. There's no editorial interpretation — just the codes a doctor actually billed Medicare for.
Concrete example: HCPCS code 99213 is "office visit, established patient, low-to-moderate complexity, ~15 minutes" — the single most common code in Medicare billing. If a primary care doctor's profile lists "Office Visit, Established Patient" as their top procedure with 800 patients, that's literally HCPCS 99213 billed 800+ times — verifiable line-by-line in the source CMS file at data.cms.gov.
The middle child of D-SNP integration. The Medicare side of your coverage is contractually aligned with a Medicaid managed-care plan run by the same parent company in the same state, so the two halves share data, share care managers, and align provider networks. But unlike a FIDE plan, HIDE doesn't always combine the two into a single ID card or a unified benefit packet. How to picture the integration spectrum: Coordination-Only (loose, the default) → HIDE (tight, the two sides actually talk to each other) → FIDE (combined, one card / one experience). Why HIDE matters: for a dual-eligible, going from Coordination-Only to HIDE typically removes most of the "did Medicaid cover that? did Medicare? do I need to call both?" moments — because the same company runs both halves and their systems share information. You may still get two cards, but the rep on the other end of the phone can answer questions about both sides. That's a meaningful upgrade in day-to-day usability without the operational complexity of a true FIDE.
State availability: HIDE plans exist where a state's Medicaid managed-care contracts align with a Medicare Advantage carrier already operating in the state. Not every state has built that alignment yet, and the available carriers vary by region. Look at the D-SNP type column on each plan card on the page above — if you see HIDE plans listed for your zip, they're usually worth a closer look than the coordination-only equivalents from the same carrier.
See also: D-SNP, FIDE, Coordination-Only D-SNP
Infections patients acquire while receiving hospital treatment — and one of the most objective quality measures CMS tracks. HAI data is reported to the CDC's NHSN and published at the facility level, covering specific infection types like CLABSI (central line infections), CAUTI (catheter-associated UTIs), SSI (surgical site infections), and C. diff. How to use this data: CMS reports HAI rates as a ratio compared to the national benchmark — a value below 1.0 means the hospital has fewer infections than expected. When we build hospital profiles, HAI data is one of the strongest signals of actual care quality because it's measured, not surveyed.
A standardized patient satisfaction survey administered to a random sample of recently discharged patients. HCAHPS measures how patients perceive their care — communication with doctors and nurses, responsiveness of staff, cleanliness, pain management, and discharge instructions. Analytical note: HCAHPS is perception-based, not outcomes-based. A hospital can score poorly on HCAHPS but have excellent clinical outcomes, and vice versa. We display HCAHPS data alongside clinical measures (infections, readmissions, mortality) so you can distinguish "patient experience" from "clinical quality" — they're related but not the same thing.
The most common Medicare Advantage plan type in our database. HMOs require in-network providers and a primary care physician referral to see specialists. What the data shows: HMOs consistently offer the lowest premiums in most markets — many $0-premium plans are HMOs. The trade-off is flexibility. If you travel frequently, see specialists without referrals, or live near a state border, the network restrictions may not work for you. In rural areas, HMO networks can also be thin — fewer providers means less choice even within the network. Check your zip code to see the HMO vs. PPO breakdown in your area.
See also: PPO
A CMS penalty program that financially punishes hospitals with higher-than-expected 30-day readmission rates for specific conditions (heart attack, heart failure, pneumonia, hip/knee replacement, COPD, CABG). Why this matters for plan comparison: if a hospital in your MA plan's network has high readmission rates, it's a signal of potential gaps in discharge planning and follow-up care. HRRP penalties are public — we include readmission data in our hospital profiles so you can factor it into your decision. A hospital that keeps readmissions low is generally coordinating care more effectively after you go home.
Your one-time, 7-month window to join Medicare: 3 months before your 65th birthday month, your birthday month, and 3 months after. Why timing within the IEP matters: if you enroll in the 3 months before your birthday, coverage starts on your birthday. Enroll during your birthday month or later, and coverage is delayed 1–3 months — leaving a gap. Missing the IEP entirely triggers permanent penalties (10%/year for Part B, 1%/month for Part D) and forces you to wait for the General Enrollment Period. If you're still working with employer coverage at 65, you may be able to delay — but get written confirmation of creditable coverage from your employer. See our enrollment dates page for the full breakdown.
Providers who have a contract with your specific MA plan — and therefore charge the plan's negotiated rates. What this means in practice: "in-network" isn't binary across plans. A doctor can be in-network for one UnitedHealthcare plan but not another UnitedHealthcare plan in the same zip code. Plan-level provider directories change annually, which is why we always recommend verifying network status directly with the provider's office — not just the plan's website — before enrolling. For HMO plans, in-network is effectively your only option (except emergencies). For PPOs, out-of-network is available but at significantly higher cost.
A permanent premium surcharge — and one of Medicare's most punitive rules. If you didn't enroll in Part B or Part D when first eligible and didn't have creditable coverage, the penalty follows you for life. The math: For Part D, it's 1% of the national base premium ($34.70 in 2026) per month you delayed. A 2-year gap = 24 months × 1% × $34.70 = $8.33/month extra, permanently. For Part B, it's 10% for every full 12-month period you were eligible but didn't enroll. These penalties compound because they're recalculated each year against the current base premium — so the dollar amount increases over time even though the percentage is fixed.
Real cost: A 24-month Part D gap in 2026 adds ~$100/year to your premium. Over 20 years of Medicare, that's $2,000+ in penalties for something that could have been avoided with a timely enrollment.
The technical name for "Extra Help" — federal assistance that reduces Part D drug costs for low-income beneficiaries. LIS isn't just a discount; at full subsidy levels, it can eliminate premiums, deductibles, and reduce copays to $0–$4.50 per prescription. Underutilization is the issue: CMS estimates millions of eligible beneficiaries haven't applied. If you qualify, it also unlocks a Special Enrollment Period to change plans any time. If there's any chance you're eligible, the application takes 10 minutes at ssa.gov.
See also: Extra Help
A CMS Star Ratings measure that tracks how consistently a Part D plan's members fill their prescriptions for chronic-disease medications — specifically diabetes drugs, cholesterol-lowering statins, and blood-pressure medications (ACE inhibitors and ARBs). The measure uses pharmacy claims to calculate the percent of members with a "proportion of days covered" of 80% or more. Why this score is more useful than it sounds: a high adherence score doesn't just mean members are organized — it means the plan is actively helping them stay on therapy. Auto-refill programs, mail-order pharmacy options, transportation benefits to the pharmacy, care-coordination calls when a refill is overdue. A 5-star adherence plan is the kind of plan that texts you a reminder; a 1-2 star plan is the kind that silently watches the lapse show up in claims data three months later. The bottom line for chronic-disease shopping: for someone managing diabetes or high blood pressure long-term, the plan that helps you take your medication is doing more for your outcomes than the plan with the lowest premium. We surface this measure prominently on condition pages for exactly that reason.
Range to expect: CMS publishes annual cut points for these measures. Plans that hit 5-star adherence on diabetes drugs typically reach the high-80s-to-low-90s percentage of members on therapy 80%+ of the year. Plans in the 1–2 star range often sit below 75%. That gap reflects real operational practices on the plan's side — outreach, pharmacy partnerships, technology — not just whether members happen to be conscientious. When two plans cost the same, the higher-adherence plan is doing more work for you.
See also: Star Rating, Part D
An MA plan that bundles Part D drug coverage into the same plan. In our database, the vast majority of Medicare Advantage plans are MAPD. Why this distinction matters: if your MA plan is MA-only (no drug coverage), you still need a standalone Part D plan to avoid the late enrollment penalty. Check the plan's benefits summary for "prescription drug coverage: Yes/No." When comparing on our site, we flag MAPD plans separately so you can see whether drug coverage is included or requires a second plan.
The private-insurer alternative to Original Medicare — and the fastest-growing segment of the Medicare market. Over 50% of eligible beneficiaries are now in MA plans, up from 30% a decade ago. MA plans must cover everything Original Medicare covers but can add benefits (dental, vision, hearing, fitness, telehealth) and structure costs differently (copays instead of coinsurance, annual MOOP limits). The trade-off we see in the data: MA plans offer financial predictability and extra benefits, but restrict you to a provider network. Original Medicare has no network but no out-of-pocket cap. Your choice depends on whether you value cost certainty (MA) or provider freedom (Original Medicare + Medigap). In competitive markets, we regularly see 40–80+ MA plans available in a single zip code — which is exactly why comparison tools like ours exist.
The annual ceiling on your out-of-pocket costs for covered services (excluding premiums). Once you hit it, the plan pays 100% for the rest of the year. This is the most underappreciated metric in plan comparison. Two $0-premium plans can have MOOPs ranging from $3,000 to $8,850 — that's a $5,850 difference in your worst-case annual exposure. MOOP matters most if you face a serious illness or hospitalization. Original Medicare has no MOOP at all, which is one of the key structural risks it carries. When we rank plans, we surface MOOP prominently because premium alone doesn't tell you how much the plan could cost in a bad year.
Comparison: A plan with a $25/month premium and $3,400 MOOP caps your worst year at $3,700. A $0-premium plan with $8,850 MOOP could cost $8,850. The "free" plan isn't necessarily cheaper.
Private supplemental insurance that plugs the gaps in Original Medicare — covering copays, coinsurance, deductibles, and (for some plans) foreign travel emergencies. Medigap plans are standardized by CMS into letter plans (A, B, C, D, F, G, K, L, M, N), meaning Plan G from Aetna covers the same things as Plan G from Mutual of Omaha — only the premium differs. Key data point: Plan G is the most popular Medigap plan since Plan F was closed to new enrollees in 2020. You cannot have both Medigap and Medicare Advantage simultaneously — it's one or the other. The Medigap vs. MA decision is one of the biggest financial choices in Medicare, and it depends heavily on your health risk tolerance, provider preferences, and local plan competition.
The contracted group of doctors, hospitals, and pharmacies your MA plan covers at in-network rates. What makes networks tricky: network breadth varies enormously between plans — even plans from the same insurer in the same zip code can have different provider networks. A "broad" network might include most local hospitals and specialists; a "narrow" network trades provider choice for lower premiums. There's no standard definition of broad vs. narrow, so the only reliable way to evaluate a network is to check whether your specific doctors and hospitals are included. Our doctor questions checklist helps with that conversation.
The CDC's infection surveillance system — and one of the most reliable data sources in hospital quality analysis. Hospitals are required to report infection rates to NHSN, and CMS publishes the results as HAI measures. Unlike patient-satisfaction surveys (which are subjective), NHSN data is lab-confirmed and standardized. When we build hospital profiles, NHSN-reported infection rates are one of the clearest signals of a facility's clinical hygiene and procedural quality.
A unique 10-digit ID number assigned to every healthcare provider — doctors, hospitals, pharmacies, group practices. Think of it as the universal key that links a provider across every CMS dataset: billing records, quality measures, plan networks, and Physician Compare. If you want to verify a specific doctor's credentials or look up their affiliations, search by NPI at npiregistry.cms.hhs.gov. It's the same identifier we use to cross-reference doctor-hospital affiliations in our data.
CMS's master registry of every Medicare-enrolled provider — the official list of names, credentials, primary specialties, taxonomy codes, practice addresses, and phone numbers. Every healthcare provider in the U.S. who bills Medicare must register in NPPES and is supposed to keep their record current. How we use it: NPPES is the foundation of every doctor profile on this site. When you see a doctor's name, specialty, address, or phone number on one of our pages, that information came from NPPES — not from a paid directory, not from a listing aggregator, not from anything we collected from a visitor. You can audit any doctor's record yourself, for free, at npiregistry.cms.hhs.gov — same data we use, presented in CMS's raw form. Honest caveat: NPPES is self-reported. Providers have 30 days by law to update their record after a change, but enforcement is loose, so it's not unusual to find a phone number that's a few months stale or a doctor still listed at a practice they left last quarter. We re-pull the file regularly to keep the lag minimal, but if a phone number on a profile rings to the wrong office, the doctor's actual current office is the source of truth.
Practical tip: when you call the phone number on a doctor profile and reach a different practice, the doctor probably moved and hasn't updated their NPPES record yet. Ask the receptionist where the doctor went, or look the name up directly on the NPI registry — moves take effect there before they propagate to most third-party directories. Doctors do eventually update because their billing depends on it, but "eventually" can mean weeks.
See also: NPI
January 1 – March 31. A second-chance window, but with restrictions most people don't realize. OEP is only for people already in a Medicare Advantage plan — you can switch to another MA plan or drop MA to return to Original Medicare + Part D. What you can't do: join MA for the first time, or switch standalone Part D plans. Think of OEP as an "escape hatch" — if you picked the wrong MA plan during AEP and your January experience confirms it (wrong network, surprise costs), you get one more change. Use it strategically, not reactively.
The government-administered Medicare program (Part A + Part B) — no private insurer, no network restrictions, see any Medicare-accepting provider in the country. The structural risk: Original Medicare has no annual out-of-pocket maximum. A serious hospitalization could cost you 20% of charges with no cap. That's the core reason ~80% of Original Medicare beneficiaries carry supplemental coverage (Medigap or employer-sponsored). The Medicare Advantage alternative trades provider freedom for cost predictability. Neither is universally "better" — it depends on your health status, provider preferences, and risk tolerance.
Providers without a contract with your specific plan. The cost impact depends on your plan type: HMO = out-of-network care is generally not covered at all (emergencies excepted). PPO = covered but at higher cost-sharing (often 40–50% coinsurance vs. 20% in-network). Original Medicare = the concept doesn't apply since there's no network. The most expensive surprise in Medicare Advantage is an unplanned out-of-network hospitalization — always verify both your doctor and the hospital they're affiliated with.
Covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health care. Most people get Part A premium-free (you or your spouse paid Medicare taxes for 10+ years of work). What Part A doesn't tell you: "premium-free" doesn't mean "cost-free." Part A has a per-benefit-period deductible (~$1,632 in 2024) and coinsurance kicks in after 60 days in the hospital. For stays over 90 days, you start drawing on limited "lifetime reserve days." These are the structural gaps that Medicare Advantage and Medigap plans exist to fill.
Covers doctor visits, outpatient care, preventive services, labs, and durable medical equipment. The standard Part B premium is $185/month in 2026 — this is a cost you pay regardless of whether you choose Original Medicare or Medicare Advantage (MA plans receive a portion of your Part B premium from CMS). Income-related surcharge: if your modified adjusted gross income exceeds $106,000 (individual) or $212,000 (couple), you pay more through IRMAA (Income-Related Monthly Adjustment Amount). The surcharge can more than double your Part B premium. IRMAA is based on your tax return from two years prior, and many people are surprised by it.
See Medicare Advantage.
See Network. "Provider network" and "network" mean the same thing in a Medicare context — the list of doctors, hospitals, and pharmacies your plan has contracts with at in-network rates. The longer form is more common on plan marketing materials and Evidence of Coverage documents; the shorter form is the everyday usage.
Prescription drug coverage offered through private insurers, available as a standalone plan (PDP) or bundled into an MA plan (MAPD). Each plan has its own formulary, premium, deductible, and pharmacy network — the variation between plans is enormous. Post-IRA landscape: the Inflation Reduction Act capped annual out-of-pocket drug costs at $2,000 starting in 2025, which fundamentally changed the Part D value calculation. Previously, people with expensive specialty drugs could pay thousands in the coverage gap. Now every plan has the same hard cap, making the key comparison variables premium, deductible, and how your specific medications are tiered on each plan's formulary.
See also: Formulary, Drug Tier, Coverage Gap
MA plans that trade higher premiums for more flexibility — no referral requirements and out-of-network coverage (at higher cost). When the data says PPO makes sense: if you travel frequently (PPOs typically cover out-of-area care), see multiple specialists without wanting to go through a gatekeeper, or live near a state border where your preferred hospital is across the line. In our plan database, PPOs average $15–$30/month higher premiums than comparable HMOs in the same zip code — but for people who use out-of-network services, that premium can pay for itself quickly.
See also: HMO
A pharmacy that has a deeper cost-sharing agreement with your Part D plan — resulting in lower copays than a "standard" in-network pharmacy. This is an easy savings most people miss. The copay difference between a preferred and standard pharmacy for the same drug on the same plan can be $5–$15 per fill. Over 12 months across multiple medications, that adds up. Check whether your regular pharmacy is "preferred" for your plan — if not, a chain pharmacy a block away might be. On our place pages, we show local pharmacy counts so you can see the retail pharmacy density in your area.
A plan's requirement that a drug or service be approved before it's covered — essentially a gatekeeping mechanism. Your doctor submits clinical justification; the plan has 72 hours (expedited) or up to 7 days (standard) to respond for Part D requests. What this means in practice: if you take a medication that requires prior auth, switching plans could mean a gap in coverage while the new plan processes the approval. When comparing plans, check whether your medications carry prior auth, step therapy, or quantity limit restrictions — this information is in each plan's formulary but rarely highlighted in marketing materials.
See also: Step Therapy, Quantity Limits
Three state-administered Medicaid programs that pay some or all of your Medicare premiums and cost-sharing if your income is below program thresholds. They are the "partial Medicaid" programs — narrower than full Medicaid, but still meaningful. QMB (Qualified Medicare Beneficiary) is the most generous: it pays your Part A and Part B premiums plus all Medicare deductibles, copays, and coinsurance, leaving you with effectively $0 out-of-pocket on Medicare-covered services. SLMB (Specified Low-Income Medicare Beneficiary) pays only your Part B premium. QI (Qualifying Individual) also pays only the Part B premium but has a slightly higher income limit, so people who fall just above SLMB sometimes still qualify for QI. Why these programs matter for D-SNP shopping: people enrolled in any of the three are "partial dual-eligibles" and can join a D-SNP. Full-benefit dual-eligibles (people on full Medicaid, not just one of these programs) typically see the deepest cost savings from a D-SNP, but partial-duals still benefit. Qualifying for any Medicare Savings Program also automatically enrolls you in the Extra Help / LIS drug subsidy — that automatic enrollment is the biggest hidden benefit. The thing most people miss: QMB, SLMB, and QI are massively underutilized. CMS estimates that millions of people who qualify never apply, often because they assume "Medicaid" means "full Medicaid" when these are narrower programs. Income and asset thresholds change each year and vary by state, so check your state Medicaid agency's current limits before assuming you don't qualify. The application typically takes 30 minutes; the savings are immediate.
Real-cost example: a single Medicare beneficiary living on Social Security just above the federal poverty level often qualifies for SLMB or QI without realizing it. That qualification eliminates the standard Part B premium ($185/month in 2026) — a $2,220-per-year savings. For someone on a fixed Social Security income, that's groceries for two months, every year, for life. And it triggers Extra Help on the drug side at the same time.
See also: D-SNP, Extra Help, LIS
Caps on how much of a drug your plan will cover per fill — for example, 30 tablets per 30 days. Quantity limits are the least-discussed formulary restriction, but they bite hardest for people whose doctor prescribes a dosage that doesn't align with the plan's limit. Example: if your plan limits a drug to 30 pills/month but your doctor prescribes 60, you'll need either a quantity limit exception (your doctor files paperwork) or an out-of-pocket purchase for the overage. This is another reason to check your specific medications against each plan's formulary before enrolling — not just "Is it covered?" but "Is it covered at the quantity I need?"
See also: Prior Authorization, Step Therapy
An out-of-cycle enrollment window triggered by a qualifying life event. Common triggers: moving to a new service area, losing employer or union coverage, qualifying for Medicaid or Extra Help, or enrolling in a 5-star plan (which allows switching any time). What most people don't realize: SEPs aren't just for emergencies — they're a strategic tool. If you gain Medicaid eligibility, that SEP lets you join a D-SNP plan immediately. If a 5-star plan is available in your area, you can switch to it at any point during the year. We flag star ratings prominently on our plan pages for exactly this reason. See our full SEP guide for qualifying events and timelines.
See SEP. Dual-eligibles have additional SEP rights — they can change D-SNPs once per quarter in the first three quarters of each calendar year, plus during Annual Enrollment.
See SNP. CMS uses the full phrase in regulations and plan documents; everyone calls them "SNPs" in conversation. Same plans, two ways of writing the name.
MA plans with restricted enrollment — you must meet specific criteria to join. Three types: D-SNP (dual-eligible for Medicare + Medicaid), C-SNP (qualifying chronic conditions), and I-SNP (institutional, for people in long-term care facilities). Why SNPs deserve attention: because they serve defined populations, SNPs often provide more targeted care coordination, lower cost-sharing, and condition-specific benefits than general-enrollment plans. In our data, SNPs (particularly D-SNPs) make up a growing share of the MA market. If you qualify for one, it should be on your comparison list — they solve problems that general plans aren't designed for.
CMS's composite quality score (1–5 stars) for MA and Part D plans, updated annually. The rating weighs healthcare outcomes, member experience, customer service, and plan administration. How we use Star Ratings in our analysis: plans rated 4+ stars are above average, and we surface them first in our leaderboards. But Star Ratings have nuances — a new plan may not have a rating yet (CMS needs 2+ years of data), and the same insurer can have a 4.5-star plan and a 2.5-star plan in the same market. Star Ratings also carry financial incentives: 5-star plans qualify for year-round enrollment via SEP, and CMS pays bonus payments to 4+ star plans, which often translates to richer benefits for members.
Data point: In many zip codes we analyze, the highest-rated plan is not the lowest-premium plan — quality and price don't correlate as strongly as you'd expect.
A cost-control mechanism requiring you to try a cheaper drug before the plan covers the one your doctor prescribed. Typically: "try the generic first; if it doesn't work, we'll approve the brand-name." The friction point: step therapy adds delays and can force you onto a medication your doctor didn't choose. If you're already stable on a specific drug and switch to a plan with step therapy requirements for that drug, you may have to "start over" with the cheaper alternative before the plan will cover your current prescription. Your doctor can request a step therapy exception — but it adds paperwork and time. Check for these restrictions in the formulary before you enroll.
See also: Prior Authorization
Healthcare visits delivered by video or phone instead of in person — most commonly used for routine follow-ups, mental-health appointments, prescription refills, and specialist consults that don't require a physical exam. Original Medicare and most Medicare Advantage plans cover telehealth at the same cost-share as an in-person visit. Many MA plans expanded telehealth benefits during the pandemic and kept them: 24/7 virtual urgent-care lines, virtual mental-health visits at $0 copay, virtual-first plan designs that route routine care through telehealth before in-person. Three practical caveats most plan brochures don't spell out:
- You need a stable internet connection. Rural broadband still has gaps. If you're not sure your home connection is up to a video visit, check what's actually available at your address at ISPReports.org.
- Your doctor must be licensed in your state on the day of the visit. If you're at home in Utah and want a telehealth visit with a Mayo Clinic specialist in Minnesota, that specialist needs a Utah license — and most don't have all 50. Most plans don't make this clear up front, and it's the most common reason a "covered" telehealth visit gets denied at billing.
- Some visits will still need an in-person follow-up. Anything that requires imaging, labs, or a hands-on exam can start virtual but won't end there. Plan accordingly so a virtual visit doesn't turn into "okay, now go to urgent care anyway."
For official Medicare telehealth guidance, see Telehealth.HHS.gov from the U.S. Department of Health & Human Services.
Most underrated MA telehealth benefit: 24/7 nurse hotlines included with no copay. They won't replace your primary care doctor, but for the 9 p.m. "should I be worried about this?" question, they're often more useful than a clinic visit two days later — and they can sometimes save a trip to the ER.
Any organization that markets Medicare plans on behalf of insurers — online comparison sites, call centers, brokers, and agents. CMS regulates TPMOs under specific marketing rules (like the "scope of appointment" requirement and prohibitions on unsolicited contact). Why this term matters for transparency: if a website recommends specific plans, they're likely a TPMO earning commissions from insurers — which can create bias toward plans that pay higher referral fees. InsuranceDataNow is not a TPMO. We display public CMS data organized by location and do not sell, enroll, or recommend specific plans. Our revenue model (advertising-supported) is disclosed in our About page. For enrollment, we direct you to Medicare.gov or 1-800-MEDICARE.
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Now that you know the terms, compare plans in your zip code.
Find Plans by Zip CodeRelated Resources
- How to Choose a Medicare Plan — Complete guide to evaluating Part C and Part D options
- Medicare Enrollment Checklist — Printable step-by-step checklist for enrollment
- Medicare Enrollment Dates & Deadlines — Key dates, timelines, and penalty calculations
- Questions to Ask Your Doctor About Medicare — Printable question list for appointments
- Our Methodology — How we source and verify CMS data
About the Reviewer
Wes Ward is the founder of InsuranceDataNow.org and reviews all content for data accuracy and methodology compliance. With 25+ years in data analytics — including work with regulated data at Ancestry.com and Zions Bancorporation — he brings enterprise-level rigor to consumer healthcare tools.