Medicare Enrollment Guide for Families
A plain-English walkthrough of Medicare Parts A, B, C, and D — who qualifies, when to enroll, and how to avoid the most common (and costly) mistakes families make.
Medicare is complicated by design — and the stakes for getting it wrong are high. A missed enrollment window can mean permanent penalties, gaps in coverage, or being locked out of the best supplement plans. This guide walks you through each part of Medicare, the enrollment timeline, and the most common (and expensive) mistakes families make — so you can make informed decisions with confidence.
Medicare at a Glance — The Four Parts
Part A — Hospital Insurance
Covers inpatient hospital stays, skilled nursing facility care (short-term), hospice care, and some home health services. Most people don't pay a premium for Part A if they or their spouse paid Medicare taxes for at least 10 years.
Part B — Medical Insurance
Covers doctor visits, outpatient care, preventive services, durable medical equipment (walkers, hospital beds, oxygen), mental health services, and ambulance rides. Everyone pays a monthly premium — the standard amount in 2026 is $185.00/month, with higher-income households paying more.
Part C — Medicare Advantage (MA)
Private insurance plans that bundle Part A, Part B, and usually Part D into one plan. Often includes extra benefits like dental, vision, hearing, and gym memberships. BUT: network restrictions apply — your parent may be limited to specific doctors and hospitals. MA plans are not the same as Original Medicare + a supplement.
Part D — Prescription Drug Coverage
Helps cover the cost of prescription medications. Offered through private insurers approved by Medicare. Each plan has its own formulary (list of covered drugs) — your parent's specific medications must be on that list. Late enrollment triggers a permanent penalty added to the monthly premium.
Medigap (Medicare Supplement) — The Missing Piece
What Medigap does
Medigap plans fill the 'gaps' in Original Medicare — deductibles, copays, and coinsurance that Medicare doesn't cover. Without a supplement or MA plan, there is NO out-of-pocket maximum — this is the biggest surprise for families new to Medicare.
When to buy Medigap
The best (and sometimes only guaranteed) window is the 6-month Medigap Open Enrollment Period, which starts the first month your parent has Part B and is 65 or older. During this window, insurers CANNOT deny coverage or charge more based on pre-existing conditions. Miss it, and in most states you can be denied or charged much more.
Medigap vs. Medicare Advantage
Medigap works WITH Original Medicare; MA REPLACES it. With Medigap, your parent can see any doctor nationwide that accepts Medicare — no referrals, no networks, no prior authorizations. With MA, they're in a managed network. The trade-off: Medigap costs more in monthly premiums but offers far more flexibility. For someone with complex or multiple conditions seeing many specialists, Medigap is usually the safer choice.
Most popular Medigap plans
Plan G (most comprehensive for new enrollees since 2020), Plan N (lower premium, some copays), and Plan G High-Deductible (lowest premium, higher out-of-pocket tradeoff). Plan F is no longer available to anyone who became eligible for Medicare after January 1, 2020.
Enrollment Windows — When & How to Sign Up
Initial Enrollment Period (IEP)
The 7-month window: 3 months before the month your parent turns 65, the month of their birthday, and 3 months after. For most people, this is THE window — miss it and you face penalties and gaps in coverage.
General Enrollment Period (GEP)
January 1 – March 31 each year, with coverage starting the following month. This is a BACKUP for people who missed their IEP. Late enrollment penalties apply — 10% higher Part B premium for each full 12-month period they were eligible but not enrolled.
Special Enrollment Period (SEP)
Available if your parent delayed enrollment because they were covered by an employer group health plan (their own or a spouse's — must be from current employment, not COBRA or retiree coverage). The SEP lasts 8 months after employment or coverage ends, whichever comes first. No late penalty if they enroll during this window.
Annual Enrollment Period (AEP) — Oct 15 – Dec 7
Each year during this window, everyone can switch between Original Medicare and Medicare Advantage, change Part D plans, or switch between MA plans. Changes take effect January 1. This is the time to review whether your parent's current coverage still fits their needs.
Medicare Advantage Open Enrollment — Jan 1 – Mar 31
If already enrolled in a Medicare Advantage plan, your parent can switch to a different MA plan OR switch back to Original Medicare (and join a Part D plan) once during this period. They CANNOT switch from Original Medicare to MA during this window.
Step-by-Step Enrollment Checklist
Step 1: Determine eligibility
Is your parent 65 or older? Under 65 with a qualifying disability (24 months of SSDI)? Any age with ESRD or ALS? Confirm before proceeding — enrolling when ineligible creates a mess to untangle.
Step 2: Create a Medicare.gov account
Go to medicare.gov and create an account for your parent (or help them do it). This account is the gateway to everything — enrollment, claims tracking, plan comparison, and replacement card requests.
Step 3: Enroll in Part A and Part B
If your parent is already receiving Social Security, they may be enrolled automatically — check their Medicare card. If not, apply online at ssa.gov/medicare, by phone at 1-800-772-1213, or in person at a local Social Security office. Do this during their IEP.
Step 4: Decide: Original Medicare + Medigap + Part D, OR Medicare Advantage
This is THE fork in the road. If choosing Original Medicare: buy a Medigap policy during the 6-month open enrollment window, THEN enroll in a standalone Part D drug plan. If choosing Medicare Advantage: find a plan that covers their doctors, hospitals, and medications — use medicare.gov/plan-compare.
Step 5: Enroll in Part D (prescription drug coverage)
Even if your parent takes no medications today, enroll in at least a low-premium Part D plan. Skipping it triggers a permanent late enrollment penalty (1% of the national base premium × number of uncovered months). The penalty never goes away and is added to every future monthly premium.
Step 6: Document everything
Save copies of all enrollment confirmations, plan documents, premium statements, and correspondence. Create a dedicated folder (physical and digital). When something goes wrong — and it does, often — having the paper trail is the difference between a 5-minute fix and weeks of phone calls.
Step 7: Set calendar reminders for AEP
Annual Enrollment Period (Oct 15 – Dec 7) EVERY YEAR. Plans change formularies, premiums, and networks annually. What's the best plan this year may not be next year. Set a recurring October 1st reminder to review coverage before AEP opens.
Common Mistakes — and How to Avoid Them
Mistake #1: Missing the Initial Enrollment Period
This is the costliest mistake families make. The Part B late penalty is 10% for each 12-month period of delay — and it's PERMANENT. The Part D penalty is also permanent. Solution: Know your parent's IEP window and enroll on time. If they're still working past 65 with employer coverage, get that in writing and confirm it qualifies as creditable coverage.
Mistake #2: Assuming Medicare covers everything
Medicare does NOT cover: long-term custodial care (nursing home or assisted living), dental care, eye exams for glasses, hearing aids, routine foot care, or medical care outside the U.S. (with rare exceptions). This gap catches families off guard — plan for these costs separately.
Mistake #3: Enrolling in Medicare Advantage without checking doctor/hospital networks
MA plans have restricted networks. If your parent's specialists, preferred hospital, or current doctors aren't in-network, switching to Original Medicare later may not be possible if they can't pass Medigap medical underwriting. Always verify network participation BEFORE enrolling in an MA plan.
Mistake #4: Not reviewing Part D coverage annually
Drug formularies change every year. A medication covered this year may not be covered next year — or may move to a higher tier with a much higher copay. During AEP (Oct 15 – Dec 7), use the Medicare Plan Finder to compare Part D plans against your parent's current medication list.
Mistake #5: Forgetting to coordinate with employer/retiree coverage
If your parent has retiree health benefits through a former employer, Medicare rules about which coverage pays first (primary vs. secondary) get complex. Making the wrong choice can leave them without coverage for months. Call 1-800-MEDICARE or speak with the employer's benefits administrator before making changes.
Mistake #6: Ignoring income-related monthly adjustment amounts (IRMAA)
Higher-income households pay more for Part B and Part D. IRMAA is based on tax returns from 2 years ago. If your parent's income has dropped since then (retirement, for example), they can file form SSA-44 to request a reduction. Many families don't know this and overpay for years.
Key Terms to Know
Premium
The monthly amount paid for coverage, regardless of whether services are used.
Deductible
The amount your parent must pay out-of-pocket before Medicare or the plan begins to pay.
Copayment / Copay
A fixed dollar amount paid for a covered service (e.g., $20 per doctor visit).
Coinsurance
A percentage of the cost paid for a covered service (e.g., 20% of the Medicare-approved amount after the deductible is met).
Out-of-Pocket Maximum
The most your parent will pay in a year before the plan covers 100%. Original Medicare has NO out-of-pocket maximum — this is why Medigap or MA coverage matters.
Formulary
The list of prescription drugs a Part D or MA plan covers, organized into tiers with different copays.
Prior Authorization
A requirement that the plan approve a service, medication, or equipment before it's covered. Common in MA plans; rare in Original Medicare.
Creditable Coverage
Health insurance coverage (usually from an employer) that is at least as good as Medicare's standard prescription drug coverage. Having it means no Part D late penalty when eventually enrolling.
Notes
Disclaimer: This guide is an educational resource designed to help families understand Medicare enrollment. It does not constitute insurance, legal, or financial advice. Medicare rules, premiums, and plan availability change annually. Always verify current information at medicare.gov or consult a licensed insurance professional. If you need help coordinating your parent's Medicare enrollment and healthcare needs, our coordinators can guide you through the process.
Provided by American Healthcare Coordination, LLC | www.americanhealthcarecoordination.com