Does Original Medicare Cover Enough? The Real Cost Gap Retirees Face

When you turn 65 and enroll in Medicare, there's a common assumption that your health coverage worries are largely behind you. After all, you've paid into the system for decades. But Original Medicare — Parts A and B — was never designed to cover everything, and the gaps it leaves can translate into real financial hardship for retirees living on fixed incomes. Understanding exactly where those gaps are, and what it costs to fill them, is one of the most important financial decisions you'll make in retirement.

Let's start with the numbers, because they matter. In 2025, Medicare Part A — your hospital insurance — charges a deductible of $1,676 per benefit period. That's not per year; it's per benefit period, which resets every time you've been out of the hospital for 60 consecutive days. If you're hospitalized twice in a year with a gap of less than 60 days between stays, you pay that deductible twice. After 60 days in the hospital, you also begin paying $419 per day in coinsurance, and after 90 days, that jumps to $838 per day for what Medicare calls your 60 lifetime reserve days. Once those reserve days are gone, they're gone permanently. On the Part B side — your outpatient and doctor coverage — you pay a $257 deductible in 2025, and then 20% of all approved costs with no upper limit. That 20% coinsurance is where many retirees get blindsided. A $100,000 cancer treatment course, for example, could leave you personally responsible for $20,000 or more.

The phrase that should concern every Medicare beneficiary is this: Original Medicare has no out-of-pocket maximum. Private insurance plans — including employer coverage and Marketplace plans — are required to cap your annual out-of-pocket costs. Medicare is not. That means a prolonged illness, a serious accident, or a chronic condition requiring frequent specialist visits can accumulate costs with no ceiling. This is the core reason supplemental coverage exists, and it's why financial planners routinely recommend that retirees budget for some form of additional protection.

So what are your options? The three main categories are Medigap (also called Medicare Supplement Insurance), Medicare Advantage (Part C), and hospital indemnity insurance. Each works differently, and choosing the wrong one for your situation is a mistake that can cost you significantly over time. Medigap plans are sold by private insurers but are federally standardized — meaning a Plan G from one company covers exactly the same benefits as a Plan G from another. In 2025, Plan G is the most comprehensive option available to new Medicare enrollees (Plan F, which covered the Part B deductible, is no longer available to people who became eligible for Medicare after January 1, 2020). Plan G covers the Part A deductible, Part A coinsurance, Part B coinsurance, skilled nursing facility coinsurance, and foreign travel emergencies, among other benefits. You still pay the Part B deductible ($257 in 2025), but after that, your cost-sharing is essentially zero for Medicare-approved services. Monthly premiums for Plan G vary widely by age, location, and insurer — typically ranging from roughly $100 to $300 per month for a 65-year-old — but the predictability it provides can be worth the cost for people who use healthcare regularly.

Medicare Advantage is a fundamentally different approach. Instead of supplementing Original Medicare, these plans replace it entirely. You still use Medicare, but your benefits are administered through a private insurer, and you typically access care through a network of providers. Medicare Advantage plans are required to cover everything Original Medicare covers, and most include extras like dental, vision, hearing, and prescription drug coverage. Many plans in 2025 have $0 monthly premiums beyond your standard Part B premium, which makes them attractive to cost-conscious retirees. However, Medicare Advantage plans do have out-of-pocket maximums — in 2025, CMS set the maximum allowable limit at $9,350 for in-network services — and you may face copays and coinsurance for every service you use. The trade-off is real: lower or no monthly premium, but potentially higher costs when you actually get sick. For relatively healthy retirees who want extra benefits and can tolerate network restrictions, Medicare Advantage may make sense. For people with serious or chronic conditions who see multiple specialists and want freedom to choose any provider, Medigap often provides better long-term value.

Hospital indemnity insurance occupies a different niche entirely. These policies pay you a fixed cash benefit — say, $200 or $500 per day — for each day you're hospitalized, regardless of what Medicare pays. They're not designed to replace Medigap or Medicare Advantage; they're typically used as a supplement to Medicare Advantage plans, which do have cost-sharing exposure. If you're on a Medicare Advantage plan with a $350 hospital copay per day for days 1 through 5, a hospital indemnity policy that pays $350 per day can effectively zero out that cost. Premiums for hospital indemnity plans are generally lower than Medigap — often $30 to $80 per month depending on benefit levels and your age — but the coverage is narrower. These plans typically only pay for inpatient hospital stays, and some have waiting periods or exclusions for pre-existing conditions. They work best as a targeted gap-filler, not as a standalone safety net.

Timing matters enormously when it comes to Medigap enrollment. When you first enroll in Medicare Part B, you have a six-month Medigap Open Enrollment Period during which insurers cannot deny you coverage or charge you more based on your health history. Miss that window, and you may face medical underwriting — meaning a company can reject your application or charge higher premiums if you have conditions like diabetes, heart disease, or a history of cancer. This is one of the most consequential and least understood rules in Medicare. If you delay enrolling in Part B because you have employer coverage, your Medigap open enrollment window starts when your Part B coverage begins, not when you turn 65. Plan accordingly.

For retirees who missed their open enrollment window and now live in certain states, there may be a second chance. Thirteen states have enacted what's known as the birthday rule, which gives Medigap policyholders a 30-day window around their birthday each year to switch to a plan with equal or lesser benefits without medical underwriting. Those states are California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. If you live in one of these states and are currently on a Medigap plan, you may be able to switch to a lower-cost plan of the same type each year without health questions — a meaningful opportunity to reduce premiums as you shop around.

The honest answer to whether you need supplemental coverage is: it depends on your health, your finances, and your risk tolerance. If you have substantial savings and could absorb a $10,000 to $20,000 medical bill without derailing your retirement, you might reasonably choose to self-insure and skip the monthly Medigap premium. But most retirees don't have that cushion, and even those who do often find that the peace of mind from predictable costs is worth the premium. What's rarely a good strategy is assuming Original Medicare alone is enough without running the actual numbers for your situation. The gaps are real, the costs are documented, and the enrollment windows are unforgiving. Taking the time to compare your options — ideally with a licensed insurance counselor through your State Health Insurance Assistance Program (SHIP), which provides free, unbiased help — can protect both your health and your financial security in retirement.