Medicare Supplement

Medigap in Aurora: how the lettered plans work

AURORA, Colo. — If you're new to Medicare or helping a parent sort through the mail piling up on the kitchen table, you've probably run into two words that sound alike but aren't the same: Medicare Advantage and Medicare Supplement. This article is about the second one — Medicare Supplement insurance, also called Medigap — and how its lettered plans (A, B, D, G, K, L, M, N) actually work.

Aurora is in Arapahoe County, and Medigap rules are largely set at the federal level, so the basics below apply whether you live near Southlands, Del Mar Park, or out toward E-470.

What Medigap is — and what it isn't

Original Medicare (Part A hospital and Part B medical) pays a big share of your covered health costs, but not all of it. You're still responsible for things like the Part A hospital deductible, the Part B 20% coinsurance, and other out-of-pocket amounts. There is no annual out-of-pocket limit built into Original Medicare.

Medigap is private insurance you can buy to help pay some of those leftover costs. According to Medicare.gov, a Medigap policy works alongside Original Medicare — Medicare pays its share first, and the Medigap policy pays some or all of what's left, depending on the letter plan you choose.

A few things Medigap is not:

• It is not Medicare Advantage (Part C). You can't have both at the same time.
• It generally does not include prescription drug coverage. For drugs, you'd usually add a separate Part D plan.
• It does not cover long-term care, most dental, vision, hearing aids, or private-duty nursing.

How the standardized letters work

Here's the part that trips people up. In most states, Medigap plans are standardized by letter. That means Plan G from one insurance company covers the exact same Medicare cost-sharing items as Plan G from another company. The benefits are set by federal rules; the price and customer service are what differ between carriers.

The current letter plans available to new enrollees are: A, B, D, G, K, L, M, and N.

• Plans C and F are no longer sold to people who became eligible for Medicare on or after January 1, 2020, because they covered the Part B deductible. If you were eligible before that date, you may still be able to buy them.
• Plans K and L have lower premiums but include an annual out-of-pocket limit and cover a smaller share of some costs.
• Plan N typically has lower premiums than Plan G but may involve small copays for office and ER visits.

Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently. Colorado follows the standard federal letter system.

The one window you don't want to miss

This is the most important sentence in this article: your Medigap Open Enrollment Period is a one-time, 6-month window that starts the month you're 65 and enrolled in Part B.

During that window, insurance companies must sell you any Medigap policy they offer at the best available rate, and they cannot turn you down or charge you more because of your health history. That's called guaranteed issue.

Outside that window, in most states, insurers can use medical underwriting — meaning they can look at your health and decide whether to sell you a policy and at what price. There are limited "guaranteed issue" situations later on (for example, if certain other coverage ends), but they're narrower than most people realize.

The common, costly mistake: assuming you can always switch Medigap plans later. Sometimes you can. Sometimes you can't. Ask before you assume.

How Medigap fits with Part D and 2026 drug costs

Because Medigap doesn't include drug coverage for new enrollees, most people with Medigap also enroll in a stand-alone Part D prescription drug plan.

A few 2026 figures worth knowing, from CMS:

• The Part D out-of-pocket cap is $2,100 in 2026. Once your covered drug costs hit that amount, you pay $0 for covered drugs the rest of the year.
• The maximum Part D deductible is $615.
• The old "donut hole" coverage gap was eliminated in 2025; Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly payments instead of paying big amounts at the pharmacy counter.
• IRMAA surcharges (higher Part B and Part D premiums for higher incomes) begin above $109,000 for a single filer in 2026.

Medigap vs. Medicare Advantage — a fair comparison

People in Arapahoe County have access to both Medicare Advantage plans and Medigap policies, and neither one is "better" in the abstract — they work differently.

• Medigap + Original Medicare + Part D: You can generally see any provider in the U.S. who accepts Medicare. Premiums are usually higher, but out-of-pocket costs at the point of care tend to be more predictable.
• Medicare Advantage (Part C): Provided by private insurers approved by Medicare. Often uses networks and prior authorization; may include extras like dental or vision. Drug coverage is frequently built in.

You can have one or the other, not both. Star Ratings exist to help you compare Advantage and Part D plans on quality, but they aren't a substitute for checking whether your doctors and medications are covered.