What happens if I miss my Medicare enrollment window?

Missing your Initial Enrollment Period can result in permanent late enrollment penalties. Part B penalties are 10% per 12-month period you were eligible but not enrolled. Part D penalties are 1% of the national base premium per month you went without creditable coverage. These penalties last for as long as you have Medicare.

Do I need Medicare if I still have employer insurance?

If your employer has 20+ employees, you can usually delay Medicare enrollment without penalty as long as you have creditable employer coverage. When that coverage ends, you get a Special Enrollment Period to sign up. If your employer has fewer than 20 employees, Medicare typically becomes primary and you should enroll at 65.

Should I choose Medicare Advantage or Original Medicare with a supplement?

There is no one-size-fits-all answer. Medicare Advantage is often $0 premium and includes extras like dental and vision, but has network restrictions. Original Medicare + Medigap gives you maximum provider freedom with predictable costs, but premiums are higher. Your health, budget, preferred doctors, and medications all factor in. This is exactly what I help people figure out.

Turning 65: Medicare Checklist

Turning 65 means Medicare is on the horizon, and the enrollment process can feel overwhelming. Miss a deadline and you could face permanent penalties. Choose the wrong plan and you might be stuck with it for a year. This guide walks you through exactly what to do, when to do it, and what to watch out for.

The basics

What Medicare covers

Part AHospital insurance: Covers inpatient hospital stays, skilled nursing, hospice, and some home health care. Most people pay $0 in premiums if they or their spouse paid Medicare taxes for 10+ years.
Part BMedical insurance: Covers doctor visits, outpatient care, preventive services, and durable medical equipment. Standard premium is $185/month in 2026 (higher for high earners).
Part CMedicare Advantage: A private-insurer alternative to Original Medicare that bundles A + B, usually includes D, and often adds dental, vision, and hearing. See the full Medicare breakdown.
Part DPrescription drugs: Standalone drug coverage. Needed if you stay on Original Medicare.

Your timeline

Your enrollment timeline

Your Initial Enrollment Period (IEP) is a 7-month window centered around your 65th birthday: 3 months before, your birthday month, and 3 months after. Here's what to do during each phase:

3 months before your 65th birthday

Sign up for Medicare Part A and Part B through ssa.gov or your local Social Security office
Review whether your current prescriptions require a Part D plan
Start comparing Medicare Advantage vs. Original Medicare + Medigap
Research plans available in your area and their provider networks

Your birthday month

Confirm your Medicare enrollment is active
Choose and enroll in a Medicare Advantage plan OR a Medigap + Part D combination
If choosing Medigap, use your guaranteed-issue window (no health questions for 6 months after Part B starts)
Set up your Medicare.gov account to manage your coverage

3 months after your 65th birthday

Deadline to complete Initial Enrollment Period enrollment
Verify all coverage is active and your doctors/pharmacies are in-network
Notify your employer if you're transitioning off employer coverage
Keep all enrollment confirmation documents

Avoid these

Common mistakes to avoid

Missing your Medigap window: You have 6 months of guaranteed issue for Medigap starting when your Part B begins. During this window, insurers cannot deny you or charge you more based on health. After it closes, they can.
Skipping Part D: Even if you don't take medications now, going without creditable drug coverage triggers a permanent late enrollment penalty of 1% per uncovered month.
Not comparing plans annually: Medicare plans change every year. Premiums, formularies, and provider networks shift. What was the best plan last year might not be best this year.

FAQ

Common questions

What happens if I miss my Medicare enrollment window?: Missing your Initial Enrollment Period can result in permanent late enrollment penalties. Part B penalties are 10% per 12-month period you were eligible but not enrolled. Part D penalties are 1% of the national base premium per month you went without creditable coverage. These penalties last for as long as you have Medicare.
Do I need Medicare if I still have employer insurance?: If your employer has 20+ employees, you can usually delay Medicare enrollment without penalty as long as you have creditable employer coverage. When that coverage ends, you get a Special Enrollment Period to sign up. If your employer has fewer than 20 employees, Medicare typically becomes primary and you should enroll at 65.
Should I choose Medicare Advantage or Original Medicare with a supplement?: There is no one-size-fits-all answer. Medicare Advantage is often $0 premium and includes extras like dental and vision, but has network restrictions. Original Medicare + Medigap gives you maximum provider freedom with predictable costs, but premiums are higher. Your health, budget, preferred doctors, and medications all factor in. This is exactly what I help people figure out.

Turning 65? Your complete Medicare enrollment checklist.