Private insurance companies sell Medicare Supplement policies, not Medicare itself

Medicare Supplement insurance (also called Medigap) is sold only by private insurance companies — not by Medicare, not by the government, and not by Social Security. When you buy a Medigap policy, you are buying from a for-profit or nonprofit insurer licensed to sell in your state. Medicare does not sell these policies, but it does set the rules about what each policy type must cover.

The insurance company you choose handles your premium payments, processes your claims, and decides which doctors and hospitals are in their network. Medicare handles your basic coverage (Part A and Part B), and your Medigap insurer handles the gaps — copayments, coinsurance, and deductibles that Medicare does not pay.

This separation matters because it means you are dealing with two separate entities. When you see a doctor, Medicare pays its share first, then your Medigap insurer pays its share according to the policy you bought. You need to understand both what Medicare covers and what your specific Medigap policy covers.

Key Takeaways

  • Private insurance companies are the only source for Medicare Supplement policies; you cannot buy them from Medicare or any government agency.
  • Each state has different insurers offering Medigap coverage, and prices vary widely even for the same policy type.
  • Medicare sets ten standard policy types (A through N), so the coverage is the same regardless of which company you choose — only the price and customer service differ.
  • You can buy Medigap from an insurance agent, directly from an insurance company website, or through a broker who represents multiple insurers.
  • The best time to buy is during your Medigap Open Enrollment Period, which lasts six months starting the month you turn 65 and enroll in Medicare Part B.

The ten standard Medigap policy types and what they cover

Medicare defines ten standardized Medigap plans labeled A, B, D, G, K, L, M, N, and two high-deductible versions of G and F (F is no longer sold to new buyers as of 2020, but existing holders can keep it). Every insurance company that sells Plan G must cover exactly the same benefits — the difference is only in price and how they handle claims.

Plan G is the most popular choice for people newly turning 65, because it covers most of what Medicare does not: Part B coinsurance, Part A coinsurance, blood transfusions, skilled nursing facility coinsurance, and hospice coinsurance. It does not cover the Part B deductible (which is $240 in 2024, though this amount changes yearly). Plan N is similar but slightly less comprehensive and usually costs less per month.

Plan A is simpler and cheaper but covers fewer gaps. Plan D, K, and L use cost-sharing (you pay part of the bill) rather than covering everything. The high-deductible versions of Plan G require you to pay a larger yearly deductible before the policy starts paying anything, which lowers your monthly premium but means higher out-of-pocket costs if you use medical services heavily.

Where to find and compare Medigap insurers in your state

Your state's insurance commissioner's office publishes a list of all insurers licensed to sell Medigap in your state, along with their phone numbers and websites. You can also search Medicare.gov's plan finder tool, which shows you insurers offering each plan type in your zip code and their current premium prices.

Insurance brokers who represent multiple companies can show you quotes from several insurers at once, which saves time if you want to compare prices across Plan G from five different companies. Some brokers charge a commission (paid by the insurance company, not by you), while others charge nothing. Ask upfront whether there is a fee.

Direct contact with an insurance company's website or phone line works too — most major insurers (Aetna, Cigna, Humana, United Healthcare, AARP/UnitedHealthcare) have online quote tools. If you work with an insurance agent who represents only one company, you will see only that company's prices, so you may pay more than you would elsewhere.

Timing your purchase: the Medigap Open Enrollment Period

Your Medigap Open Enrollment Period is the six-month window starting the month you turn 65 and enroll in Medicare Part B. During this period, any insurance company must sell you any Medigap plan at the same price they charge everyone else your age — they cannot deny you, charge you more, or exclude pre-existing conditions.

If you miss this window, you can still buy Medigap later, but the rules change. Some states allow insurers to charge you more based on your health history, and some insurers may refuse to sell to you at all. A few states have different rules, so check with your state insurance commissioner's office if you are past your six-month window.

Buying during your Open Enrollment Period is almost always the cheapest and safest choice. If you are still working and have employer health coverage, your Open Enrollment Period may start later — when you actually retire and enroll in Medicare Part B, not when you turn 65.

What to expect when you contact an insurer

When you call or visit an insurer's website, have your Medicare card handy. You will be asked which plan type you want (A, G, N, etc.), your age, your zip code, and whether you smoke. The insurer will quote you a monthly premium and explain what the policy covers and does not cover.

Ask about the insurer's process for paying claims — do they receive claims directly from your doctor's office, or do you submit them? Ask how you reach customer service if you have a question about coverage. Some insurers have 24/7 phone lines; others have limited hours. Read online reviews from current customers, especially about how quickly claims are paid.

Once you decide, the insurer will send you an enrollment form. You sign it, return it, and your coverage usually starts on the first day of the following month. You will receive an insurance card in the mail before your coverage begins.

How Medigap premiums are calculated and what affects your price

Three main factors affect what you pay: your age, your location (zip code), and whether you smoke. Some insurers also consider your health history if you are buying outside your Open Enrollment Period. During your Open Enrollment Period, all insurers must charge the same price for the same plan in your area — but prices vary between zip codes and between states.

Insurers use one of three pricing methods: community-rated (everyone in your area pays the same regardless of age), age-rated (older people pay more), or issue-age-rated (your price is based on your age when you buy, then stays the same as you age). Issue-age-rated plans are often cheaper when you first buy but may increase faster over time than age-rated plans.

Your premium may increase each year due to inflation and claims experience, but these increases are not based on your individual health — they explore to everyone in your plan. If you switch to a different insurer or a different plan type, you start fresh with a new premium based on your current age and health status.

Special situations: employer coverage, Medicaid, and life changes

If you have retiree health coverage from a former employer, you may not need Medigap at all — your employer plan may cover the gaps that Medigap would. Before you buy Medigap, contact your employer's benefits office to understand what your retiree coverage includes and whether buying Medigap would duplicate coverage.

If you are on Medicaid (your state's program for low-income people), Medicaid may cover some of the gaps that Medigap would, so buying Medigap could be unnecessary. Contact your state Medicaid office to learn what your coverage includes.

If you move to a different state, your current Medigap policy may not be valid there. Contact your insurer to ask whether they sell in your new state. If they do not, you will need to buy a new policy from an insurer in your new state. Depending on your age and health, you may or may not be able to switch plans without medical underwriting.

Frequently Asked Questions

Can I buy Medigap from Medicare directly?

No. Medicare sets the rules about what each Medigap plan must cover, but only private insurance companies sell the actual policies. You must buy from a licensed insurance company in your state.

Do all insurance companies charge the same price for the same Medigap plan?

During your Open Enrollment Period, yes — all insurers must charge the same price for Plan G (or whichever plan you choose) in your area. Outside your Open Enrollment Period, prices vary widely between insurers, so comparing quotes is important.

What happens if I buy Medigap after my Open Enrollment Period ends?

You can still buy, but insurers may charge you more based on your health history, or they may refuse to sell to you. Some states have protections that limit this; others do not. Contact your state insurance commissioner's office to learn your state's rules.

Can I switch from one Medigap insurer to another?

Yes, you can switch at any time. However, if you switch outside your Open Enrollment Period, the new insurer may charge you more or deny you based on your health. Switching during your Open Enrollment Period (if you are still within it) carries no penalty.

Is AARP the same as a Medigap insurance company?

AARP does not sell insurance directly. AARP partners with UnitedHealthcare to sell Medigap policies under the AARP brand. You are buying from UnitedHealthcare, not from AARP, though AARP membership may may have access to you for discounts on the premium.