Compass Learning Center
Start with what you want to understand. Every topic below is general Medicare education, written to be read once and remembered.
Part A helps cover inpatient hospital care. Part B helps cover doctor visits and outpatient services. Part C, also called Medicare Advantage, is coverage offered by private insurance companies approved by Medicare. Part D helps cover prescription medications.
Medicare Advantage plans provide your Part A and Part B coverage through a private plan, often with additional benefits and a provider network. Because networks and benefits are local, two people in neighboring counties may have very different options.
Medicare Supplement coverage works alongside Original Medicare to help with certain out-of-pocket costs. It does not include prescription coverage, so many people pair it with a separate Part D plan. Eligibility rules and pricing vary by state and timing.
Each Part D plan publishes a formulary: the list of medications it covers, and the tier each medication falls into. Your cost for the same prescription can differ meaningfully between plans and between pharmacies.
Costs generally fall into premiums, deductibles, copays, coinsurance and annual out-of-pocket limits. Understanding how these work together matters more than comparing a single number.
There are specific windows to enroll in or change Medicare coverage, including your Initial Enrollment Period, the Annual Enrollment Period each fall, and Special Enrollment Periods triggered by certain life events.
Provider participation can change from year to year. Before choosing coverage, it is worth confirming that the physicians, hospitals and facilities you rely on participate under the coverage you are considering.
Formularies, drug tiers, preferred pharmacies, prior authorization and quantity limits all influence what you pay and how you access a medication.
Your plan sends an Annual Notice of Change each fall describing what will be different next year. It is one of the most useful documents you receive, and one of the most commonly set aside unread.
Premiums, copays, covered medications, pharmacy pricing, provider participation, extra benefits and plan availability may all change annually.
Begin by understanding how the parts fit together, when you are eligible, and which decisions have timing rules. There is no need to decide everything in one sitting.
Each year, review your costs, your medications, your providers and whether your health or priorities have changed. An annual review is a healthcare decision, not paperwork.
Coverage compared
After you meet the Part B deductible, Original Medicare generally pays 80% of approved costs for covered services and you are responsible for the remaining 20%, with no annual out-of-pocket limit. That single fact drives most of the decisions people make about additional coverage.
Medicare pays
80%
Of the Medicare-approved amount for most covered Part B services, after the deductible.
You pay
20%
Coinsurance with no yearly cap under Original Medicare alone. Additional coverage exists to help manage this share.
| Coverage | Original Medicare (A & B) | Medicare Advantage (Part C) | Original Medicare + Medigap + Part D |
|---|---|---|---|
| Hospital care (Part A) | Included | Included | Included |
| Doctor & outpatient care (Part B) | Included | Included | Included |
| Prescription drugs | Not included | Often included | Through a separate Part D plan |
| Yearly out-of-pocket limit | None | Required by Medicare | Varies by Medigap plan letter |
| Provider network | Any provider that accepts Medicare | Plan network (HMO or PPO) | Any provider that accepts Medicare |
| Routine dental, vision, hearing, fitness | Generally not covered | Varies by plan | Generally not covered |
This table is general Medicare education. Benefits, networks and costs differ by plan and by county, and every plan must be reviewed on its own terms.
Types of coverage
Availability depends on where you live and, for some categories, on whether you meet eligibility criteria.
Care is coordinated within a local network, often with a primary care doctor at the center. Out-of-network care is generally covered only in emergencies.
More flexibility to see out-of-network providers, usually at a higher share of the cost than in-network care.
Many Medicare Advantage plans combine medical and Part D prescription coverage in one plan, so there is one card and one formulary to review.
Some plans exclude Part D. These are typically considered by people with other creditable drug coverage, such as VA benefits or an employer plan.
Sometimes called giveback plans, these reduce the Part B premium withheld from your Social Security payment. These plans may differ in cost-sharing, provider networks and additional benefits, so the premium reduction should be evaluated alongside the plan's overall coverage.
D-SNPs serve people eligible for both Medicare and Medicaid. C-SNPs serve people with certain chronic conditions. Both require that you meet eligibility criteria to enroll.
Timing
Medicare sets specific windows. Knowing which one applies to you prevents rushed decisions and late penalties.
7 months
Around your 65th birthday: the three months before your birthday month, your birthday month, and the three months after.
October 15 – December 7
Each fall you may join, switch or drop a Medicare Advantage or Part D plan for the year ahead. Changes take effect January 1.
January 1 – March 31
If you are already in a Medicare Advantage plan, you may change plans once or return to Original Medicare.
Life events
Moving, losing employer coverage, gaining or losing Medicaid or Extra Help, and other qualifying events can open a window outside the usual dates.
Help with costs
A federal program that can reduce Part D premiums, deductibles and prescription copays for people who qualify based on income and resources. Apply through Social Security.
Medicaid is a joint federal and state program that can help with medical costs. Eligibility levels are set by your state, and people with both Medicare and Medicaid may qualify for a D-SNP.
An option that spreads your out-of-pocket Part D drug costs into monthly payments across the calendar year instead of paying large amounts at the pharmacy counter.
The same medication can cost different amounts at a preferred in-network pharmacy, a standard pharmacy, or through a plan's mail-order service. Checking all three is often worthwhile.
State-run programs that may help pay Part A and Part B premiums, and in some cases deductibles and coinsurance, for people who meet income limits.
Every state has a State Health Insurance Assistance Program offering no-cost, unbiased Medicare counseling. You may also call 1-800-MEDICARE (TTY 1-877-486-2048) or visit Medicare.gov.