If you've spent any time researching Medicare Supplement insurance — commonly called Medigap — you've probably noticed that the sheer number of lettered plans can feel overwhelming. Plans A, B, D, G, K, L, M, and N are all currently sold to new enrollees, and each one covers a different combination of Medicare's cost-sharing gaps. The honest answer to "which plan is best" is that it depends on your health, your budget, and how much financial unpredictability you can tolerate. But there are clear patterns that help most people narrow the field quickly.
Let's start with the most popular choice among new enrollees in 2026: Plan G. This plan covers virtually everything Medicare doesn't — including the Part A hospital deductible ($1,676 per benefit period in 2026), Part B coinsurance (the 20% you'd otherwise owe on every doctor visit and outpatient service), skilled nursing facility coinsurance, and even foreign travel emergency care up to plan limits. The only gap Plan G leaves is the Part B annual deductible, which is $257 in 2026. You pay that once a year, and after that, your out-of-pocket costs for Medicare-covered services are essentially zero. For someone who sees specialists regularly, takes infusions, or has a chronic condition requiring frequent outpatient care, Plan G's predictability is genuinely valuable. Monthly premiums for Plan G vary significantly by age, location, and insurer — a 65-year-old woman in a mid-sized city might pay anywhere from $110 to $180 per month — but the coverage itself is standardized by federal law, meaning every insurer's Plan G covers exactly the same benefits.
Plan F was the gold standard before January 1, 2020, because it also covered that Part B deductible, making it a true zero-out-of-pocket plan. But federal law (the Medicare Access and CHIP Reauthorization Act) prohibited insurers from selling Plan F or Plan C to anyone who became eligible for Medicare on or after January 1, 2020. If you turned 65 before that date and enrolled in Plan F, you can keep it — and many people do. But if you're newly eligible for Medicare, Plan F is simply not available to you. Plan G is the functional equivalent for today's enrollees, with that one $257 annual deductible being the only difference.
Plan N is the second option worth serious consideration, particularly for beneficiaries who are in good health and want to reduce their monthly premium. Plan N covers the same core benefits as Plan G — Part A deductible, skilled nursing coinsurance, foreign travel emergency — but it introduces cost-sharing at the point of service. You'll pay up to $20 for office visits and up to $50 for emergency room visits (waived if you're admitted). Critically, Plan N does not cover Part B excess charges, which are the additional amounts that doctors who don't accept Medicare assignment can legally charge above Medicare's approved rate — up to 15% more. In states that prohibit excess charges (including Connecticut, Massachusetts, Minnesota, New York, Ohio, Pennsylvania, Rhode Island, and Vermont), this distinction is irrelevant. But in states where excess charges are allowed, choosing Plan N means you need to be careful about which providers you see. The premium savings with Plan N can be meaningful — often $30 to $60 less per month than Plan G for the same age and location — so for someone who rarely visits the doctor and lives in an excess-charge-free state, Plan N can be a smart financial choice over time.
Plans K and L are sometimes marketed as budget-friendly options, but they work very differently from Plans G and N. Rather than covering specific cost-sharing items in full, Plans K and L cover a percentage of your costs — Plan K covers 50% of most gaps, Plan L covers 75% — and both have annual out-of-pocket maximums ($7,220 for Plan K and $3,610 for Plan L in 2026). These plans can work for someone who is very healthy and primarily wants catastrophic protection, but the exposure to ongoing cost-sharing can add up quickly if you have a significant health event. Most financial advisors who specialize in Medicare planning suggest that Plans G and N offer a better balance of protection and cost for the majority of beneficiaries.
One of the most expensive mistakes people make with Medigap is waiting too long to enroll. Your guaranteed issue window — the six-month period starting the month you turn 65 and enroll in Medicare Part B — is the only time federal law requires insurers to sell you any Medigap plan at standard rates, regardless of your health history. Miss that window, and insurers in most states can ask about pre-existing conditions, charge you more, or simply decline to cover you. There are some exceptions: if you lose employer coverage, drop a Medicare Advantage plan during a valid Special Enrollment Period, or move out of your plan's service area, you may qualify for a guaranteed issue right to buy certain Medigap plans. But these rights are narrower than most people realize, and they don't apply to every plan letter.
A handful of states offer additional protections worth knowing about. Thirteen states — California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon — have what's called a birthday rule, which gives you a 30-day window each year around your birthday to switch to a Medigap plan with equal or lesser benefits without medical underwriting. This is a significant consumer protection that lets you shop for lower premiums as you age without risking denial. New York and Massachusetts have their own unique rules that provide year-round guaranteed issue rights for Medigap, making those states unusually consumer-friendly for supplement coverage.
Pricing is where many people get tripped up, because Medigap premiums are not regulated the same way the benefits are. Insurers use three different pricing methods: community-rated (everyone pays the same regardless of age), issue-age-rated (your premium is based on your age when you buy, and doesn't increase just because you get older), and attained-age-rated (your premium increases as you age). Attained-age-rated plans often have the lowest initial premiums, which makes them look attractive at 65, but they can become significantly more expensive by your mid-70s and beyond. When comparing quotes, always ask which pricing method the insurer uses — it matters more over a 10- or 20-year horizon than the initial monthly premium does.
Finally, remember that Medigap plans do not include prescription drug coverage. If you enroll in a Medigap plan, you'll need to separately enroll in a Medicare Part D prescription drug plan to avoid the late enrollment penalty — which is 1% of the national base beneficiary premium for every month you go without creditable drug coverage. In 2026, the Part D out-of-pocket cap is $2,000 annually under the Inflation Reduction Act changes, which has made Part D more valuable than it used to be. Pairing a solid Plan G or Plan N with a well-matched Part D plan gives most beneficiaries comprehensive, predictable coverage across both medical and prescription costs. The Medicare Plan Finder tool at Medicare.gov allows you to compare Part D plans side by side based on your specific medications and preferred pharmacy.