01Step one
You stay on Original Medicare
Medicare pays its share of a covered hospital or medical bill first, exactly as it would without the policy. A Medigap policy never replaces Parts A and B.
Medigap
Medicare Supplement, and the window that decides your price.
A Medigap policy pays part of what Original Medicare leaves you owing. The benefits are standardized by letter, so the shopping is about price, the insurer, and above all, timing.
Your one-time 6-month windowMedigap open enrollment starts the first month you are 65 or older and enrolled in Part B, and runs six months. Inside it, no insurer can turn you down or charge you more because of your health. After it closes, most states allow medical underwriting.
How it works
Medicare pays first. The policy pays part of the rest.
Medigap is not a plan you use instead of Medicare. It sits behind Original Medicare and absorbs a share of the cost sharing Medicare leaves you.
02Step two
Medigap pays the leftovers it covers
The policy picks up costs Medicare leaves you, such as coinsurance, copays, and depending on the plan letter, deductibles and the Part B excess charges some providers bill.
03Step three
You add drug coverage separately
Medigap policies sold today cannot include prescription drug coverage. If you want it, you enroll in a standalone Part D plan alongside the policy.
04The trade
You keep nationwide access
There is no network. Any provider in the country who accepts Medicare accepts your Medigap policy, and you do not need a referral to see a specialist.
Standardized by letter
Same letter, same basic benefits, different price.
- In most states, Medigap plans are standardized and named by letter, currently Plan A through Plan N. Every insurer selling a given letter must provide the same set of basic benefits for that letter.
- Because the benefits are fixed by letter, the differences between insurers selling the same plan are price, rate-increase history, and customer service.
- Massachusetts, Minnesota, and Wisconsin standardize their Medigap policies differently from the rest of the country.
- People who first became eligible for Medicare on or after January 1, 2020 cannot buy a policy that covers the Part B deductible, which is why Plan F is closed to that group and Plan G is the closest alternative.
- A Medigap policy covers one person. Spouses each buy their own policy.
- As long as you pay the premium, a Medigap policy is guaranteed renewable, meaning the insurer cannot drop you because your health changed.
What it does not do
Medigap fills gaps in Medicare, not gaps in life.
A Medigap policy pays a share of what Original Medicare covers. If Medicare does not cover a service at all, the policy generally does not pay for it either. These are the categories people most often expect to be included and are not.
- Prescription drugs, which come from a separate Part D plan
- Routine dental care, routine eye exams for glasses, and hearing aids
- Long-term custodial care, such as help with daily activities in a nursing home
- Private-duty nursing
- Anything Original Medicare itself does not cover, since Medigap pays a share of Medicare-covered costs
The numbers that matter
Timing, in four figures.
- Medigap open enrollment, starting with Part B at 65 or older
- 6 months
- that window happens, and it does not reopen
- Once
- the standardized plan letters sold in most states
- A to N
- without creditable drug coverage can trigger a Part D penalty
- 63 days
Good to know
Questions people ask about Medigap.
What is the 6-month Medigap open enrollment window?
Your Medigap open enrollment period lasts six months and starts the first month you are both 65 or older and enrolled in Part B. During that window an insurer must sell you any Medigap policy it offers, at the same price it charges a healthy person of your age, and cannot refuse you or make you wait for coverage of a pre-existing condition beyond the limited waiting period the law allows. This window happens once and does not repeat.
What if I apply after that window closes?
Outside the open enrollment window, and outside a guaranteed issue situation, insurers in most states may use medical underwriting. That means they can ask about your health, charge more, or decline the application. Certain events, such as losing employer coverage or a Medicare Advantage plan leaving your area, create guaranteed issue rights that protect you, and a few states give residents broader rights than federal law requires.
Can I have both Medigap and a Medicare Advantage plan?
No. A Medigap policy only works with Original Medicare. It pays nothing toward the cost sharing of a Medicare Advantage plan, and it is illegal for someone to sell you a Medigap policy while you are in an Advantage plan unless you are leaving it.
How are Medigap premiums priced?
Insurers use one of three approaches: community rated, where everyone pays the same regardless of age; issue age rated, where your premium is based on the age you were when you bought the policy; and attained age rated, where the premium rises as you get older. Ask which method a policy uses, because two policies with the same letter and a similar premium today can diverge substantially over a decade.
Do I need a Part D plan if I have Medigap?
You are not required to have one, but going without creditable drug coverage for 63 days or more in a row can trigger a Part D late enrollment penalty that is added to your premium for as long as you have Part D. Most people on Medigap enroll in a standalone Part D plan for that reason.
Medigap
See the Medicare Supplement policies sold in your state.
Enter your ZIP code to compare available plan letters and the insurers offering them.