What Is Medicare Supplement Insurance? A Guide to Medigap

Medicare Supplement Insurance, or Medigap, is sold by private insurers to help pay certain out-of-pocket costs under Original Medicare. It is not Medicare Advantage or stand-alone medical insurance.

1. How Does Medigap Work?

You need Medicare Parts A and B and generally continue paying the Part B premium, plus a Medigap premium. Original Medicare processes covered care first; Medigap then pays eligible deductibles, copays or coinsurance according to the plan letter. Each policy covers one person, so spouses apply and pay separately.

2. What Can It Help Pay?

Depending on the letter, benefits may include Part A hospital coinsurance, Part B coinsurance, the first three pints of blood, hospice or skilled nursing coinsurance, the Part A deductible, Part B excess charges or limited foreign-travel emergencies. Benefits differ by letter.

3. What Is Usually Not Covered?

Outpatient prescription drugs, routine dental and vision, eyeglasses, hearing aids, long-term custodial care and private-duty nursing generally are not covered. New Medigap policies sold after 2006 do not include Part D; a separate drug plan is generally needed. Medigap generally does not pay for services Original Medicare does not cover, with limited exceptions such as some foreign emergencies.

4. Standardized Plan Letters

Most states use standardized plans A, B, C, D, F, G, K, L, M and N. The same letter offers the same standardized medical benefits across insurers, although premiums, pricing, discounts and service differ. Massachusetts, Minnesota and Wisconsin use different standards. Medigap plan letters are not the same as Medicare Parts A, B or D.

5. Plans G, N and F

Plan G generally covers Plan F's standardized benefits except the Part B deductible. Plan N may cost less but may require office or emergency copays and does not cover the Part B deductible or excess charges. People newly eligible for Medicare on or after January 1, 2020 generally cannot buy plans C or F that cover the Part B deductible; earlier eligibility may preserve options.

6. Selected 2026 Amounts

For 2026, the Part B deductible is $283; high-deductible Plan G's deductible is $2,950; and Plan K and L annual out-of-pocket limits are $8,000 and $4,000 respectively. Medigap premiums are additional and vary. These are 2026 figures; later-year amounts can differ.

7. The Six-Month Open Enrollment Period

The federal Medigap open enrollment period is a one-time six-month period generally starting when you are at least 65 and Part B begins. During it, insurers generally cannot deny or charge more because of past or current health for available Medigap plans in your state. This is not the annual October 15–December 7 Medicare Open Enrollment.

8. Applying Later

Outside that period, insurers may use medical underwriting unless a guaranteed-issue right or stronger state protection applies. Certain losses of employer supplemental coverage, plan exits or Medicare Advantage trial rights may create limited federal protections. Confirm the new policy before canceling old coverage.

9. Travel, Part D and Medicare Advantage

Original Medicare generally offers flexibility among U.S. providers accepting Medicare. Some Medigap letters provide limited foreign emergency benefits. Medigap does not replace Part D and cannot pay Medicare Advantage copays. Before leaving Medicare Advantage, check your Medigap rights.

10. Compare and Apply

Confirm enrollment timing and guaranteed-issue rights, choose a letter, compare premiums, pricing, discounts, insurer service and rate history, and arrange Part D. Confirm approval and effective dates before changing existing coverage.

This is general education, not legal, tax, medical or individual insurance advice. Verify current plan options, underwriting, state rules and premiums with Medicare and the insurer.