Turning 65 changes your health insurance situation completely. Medicare eligibility opens up — but Medicare isn’t a single plan you simply enroll in. It’s a system with multiple parts, optional additions, private plan alternatives, and enrollment rules that, if missed, can result in permanent premium penalties.
Getting your Medicare coverage right at 65 saves money, avoids coverage gaps, and prevents the kind of surprises that cost people thousands of dollars at exactly the wrong moment. Here’s how to navigate it.
Medicare Parts A, B, C, and D
- Part A (Hospital Insurance) — covers inpatient hospital stays, skilled nursing facility care following a qualifying hospital stay, hospice, and some home health care. Most people don’t pay a premium for Part A if they or their spouse have at least 40 quarters of Medicare-covered work history.
- Part B (Medical Insurance) — covers outpatient care, doctor visits, preventive services, durable medical equipment, and some home health care. The standard 2026 premium is approximately $185/month, though higher earners pay more through IRMAA.
- Part C (Medicare Advantage) — private insurance plans approved by Medicare that provide Part A and Part B coverage, typically with added benefits. Discussed in detail below.
- Part D (Prescription Drug Coverage) — standalone prescription drug plans added to Original Medicare, or included in Medicare Advantage plans.
Enrollment — Timing Is More Consequential Than Most People Realize
Your Initial Enrollment Period (IEP) is a 7-month window: 3 months before your 65th birthday month, the month of your birthday, and 3 months after. Miss this window without qualifying for a Special Enrollment Period, and you face permanent late enrollment penalties:
- Part B late penalty: 10% added to your monthly premium for every 12-month period you delayed without creditable employer coverage. This penalty never goes away.
- Part D late penalty: 1% of the national base beneficiary premium per month of late enrollment, also permanent.
Exceptions apply for those still covered by an employer group health plan through active employment. If you or your spouse is still working and has employer coverage, you can delay Part B without penalty until that coverage ends — but you must enroll in Part B within 8 months of losing employer coverage.
💡 COBRA doesn’t count: COBRA coverage and marketplace/ACA plans do not count as creditable coverage for avoiding Medicare late enrollment penalties. If you lose employer coverage, your 8-month Special Enrollment Period clock starts — don’t delay.
Medicare Supplement (Medigap) Plans
Original Medicare (Parts A and B) covers roughly 80% of most medical costs — leaving 20% as your responsibility with no annual out-of-pocket cap. A Medicare Supplement (Medigap) policy fills some or all of those gaps.
Medigap plans are standardized by letter — Plan G covers the most gaps for new Medicare enrollees in 2026 (since Plan F was discontinued for new enrollees). Plan N offers lower premiums with some cost-sharing remaining.
Medigap plans have no network restrictions — any provider who accepts Medicare accepts your Medigap plan. For people who travel, have complex medical needs, or want predictable out-of-pocket costs, this is a significant advantage over Medicare Advantage.
The best time to buy Medigap is during your Open Enrollment Period — the 6-month window starting when you turn 65 and enroll in Part B. During this window, insurers cannot deny you coverage or charge more based on health conditions. After this window, medical underwriting applies in most states.
Medicare Advantage — The Alternative Approach
Medicare Advantage (Part C) plans are private insurance alternatives to Original Medicare. You still pay your Part B premium, but coverage is delivered through the private plan rather than directly through Medicare. Most plans include prescription drug coverage and often add dental, vision, hearing, and fitness benefits.
Medicare Advantage appeals on premium — many plans have $0 additional premium beyond the Part B payment. The trade-off is network restrictions, prior authorization requirements for some procedures, and variable out-of-pocket costs.
Medicare Advantage vs. Medigap Supplement — The Real Comparison
| Feature | Medicare Advantage | Medigap + Part D |
|---|---|---|
| Monthly premium | Often $0 beyond Part B | $80–$300+/month |
| Doctor/hospital choice | Network only (HMO/PPO) | Any Medicare provider |
| Out-of-pocket max | Yes ($8,850 in-network 2026) | Plan G: very low (deductible only) |
| Prior authorization | Common | Not applicable |
| Best for | Healthy seniors, cost-focused | Complex health needs, travel |
Part D — Prescription Drug Coverage
If you choose Original Medicare with a Medigap plan, you’ll need a separate Part D plan for prescription drug coverage. Part D plans vary significantly in premiums, covered drugs (formulary), and pharmacy networks. Use Medicare’s Plan Finder tool at medicare.gov annually during Open Enrollment (October 15 – December 7) to ensure your plan still covers your medications at the lowest cost. Plans change formularies annually — what was the best plan last year may not be this year.
What Medicare Actually Costs in 2026
- Part A: $0 for most people (40+ work quarters)
- Part B standard premium: ~$185/month (higher with IRMAA for incomes above $106,000 individual/$212,000 married)
- Medigap Plan G: approximately $100–$250/month depending on age, gender, location, and insurer
- Part D: varies by plan, typically $20–$80/month
- Medicare Advantage: $0–$60/month premium for most plans, plus cost-sharing at time of service
Frequently Asked Questions
Q: If I have a Medicare Advantage plan, can I switch to Medigap later?
You can switch during the Annual Enrollment Period (Oct 15–Dec 7), but switching from Medicare Advantage back to Original Medicare and then applying for Medigap will require medical underwriting in most states — and can be denied or priced based on health conditions. This is a strong argument for starting with Medigap if you have any significant health conditions and buying during Open Enrollment when guaranteed issue applies.
Q: I’m still on my spouse’s employer insurance at 65. Do I need Medicare?
If your spouse’s employer has 20+ employees, the employer plan is primary and Medicare is secondary. You can delay Medicare enrollment without penalty while you have that active employer coverage. If the employer has fewer than 20 employees, Medicare becomes primary and you should enroll. When your spouse retires, you have 8 months to enroll in Medicare without penalty.
Q: Is Medicare coverage good enough or do I need supplemental coverage?
Original Medicare alone leaves you with unlimited exposure — there’s no out-of-pocket cap. Without either a Medigap policy or a Medicare Advantage plan with an out-of-pocket maximum, a serious illness or extended hospitalization could result in very large bills. Most financial advisors recommend at minimum a Medicare Advantage plan with an annual OOP cap, or Original Medicare plus Plan G Medigap for those who want maximum coverage certainty.