Medicare Supplement Plan K: Coverage, Costs, Pros & Cons

Medicare Supplement Plan K is a private policy that pays part of what Original Medicare leaves behind. Part A covers hospital care and Part B covers doctor visits, but both leave you owing deductibles and co-insurance.

Plans K and L are the only two of the 10 standardized Medigap plans with a yearly spending cap, and Plan K's is $8,000 in 2026. Your half of the Part A deductible counts toward it. So does your half of Part B, blood, hospice and skilled nursing co-insurance. The Part B deductible and your premiums don't count. After you reach the cap and pay the Part B deductible, Plan K pays 100% of Medicare-covered costs for the rest of the calendar year.

Enrollees who rarely use Medicare come out ahead with Plan K. At 65 on issue age pricing, Plan K's average premiums are $1,726 a year lower than Plan G's. One hospital stay plus $8,584 in Medicare-approved Part B care after the deductible erases that saving. You'd need heavy use to reach the $8,000 cap, such as a skilled nursing stay of about three months.

The average Medicare Supplement Plan K premium for a 65-year-old on issue age pricing is $95 a month. With issue age pricing, your age when you buy sets the premium, and it won't rise as you age. It can still go up with inflation, per Medicare's Medigap guide.

Pricing method matters most at 65, when community pricing averages $32 a month more than issue age pricing. For someone buying at 75, the three methods average within $3 of each other, from $137 to $140 a month.

*Figures are national averages across the insurers in MoneyGeek's data. A community-rated policy charges buyers of any age the same premium. The $10 gap in the community column comes from averaging different policies at each age.

Your state can change your Plan K premium by more than $1,600 a year. At 65, the cheapest plan in MoneyGeek's data costs $66 a month in Utah, and the most expensive costs $204 a month in Pennsylvania, a yearly gap of $1,656.

New York, Vermont, Maine and four other states have only community-rated Plan K policies in MoneyGeek's data. Under community rating, buyers of every age pay the same premium for the same policy. Inflation can still raise that premium, per Medicare's Medigap guide.

*MoneyGeek's data has only community-rated Plan K policies in Arkansas, Connecticut, Idaho, Maine, New York, Vermont and Washington, so those states show one figure for both ages. Florida, Georgia, Missouri and New Hampshire have a single Plan K premium at each age in the data, so each age shows one figure.

Plan K pays all of your Part A hospital co-insurance and covers up to 365 extra hospital days after Medicare benefits end. For most other covered costs, including the Part A deductible and Part B co-insurance, Plan K pays half and you pay half.

In a year with frequent care, your half adds up. Once your share reaches $8,000 and you've paid the Part B deductible, Plan K pays 100% of Medicare-covered costs through the end of the calendar year.

Plan K leaves you paying the Part B deductible, excess charges and emergency care outside the U.S. No Medigap plan sold to new Medicare enrollees has covered the Part B deductible since 2020. For the other two, Plan G covers excess charges, and Plans G and N both pay 80% of emergency care abroad.

• Part B deductible: You pay the full $283 (2026, per CMS) before Plan K starts paying toward Part B costs.
• Part B excess charges: A provider who doesn't accept Medicare assignment can bill up to 15% above the Medicare-approved amount, and Plan K doesn't pay that extra.
• Foreign travel emergency: Plan K pays nothing for emergency care outside the U.S.

How often you use Medicare and how much you'll pay each month decide which of these plans fits. Plans G and N need no cap, since they pay 100% of Part A and Part B co-insurance, but both cost more. At 65 on issue age pricing, Plan G averages $239 a month and Plan N averages $188, compared with $95 for Plan K.

Plan L is the middle option. It pays 75% of most Medicare costs instead of 50%, and its cap is $4,000 instead of $8,000. At 65 on issue age pricing, Plan L averages $143 a month, $48 more than Plan K. Plans C and F were the only plans that covered the Part B deductible. People first eligible for Medicare on or after January 1, 2020, can't buy either one.

*Plan N covers 100% of Part B co-insurance, though you pay up to $20 for some office visits and up to $50 for emergency room visits that don't lead to inpatient admission.

*Figures in both tables are national averages across the insurers in MoneyGeek's data. A community-rated policy charges buyers of any age the same premium, so community figures that differ between the two tables come from averaging different policies at each age.

Your six-month Medigap open enrollment window starts the first day of the month you turn 65 and are enrolled in Part B, per Medicare.gov. During it, insurers can't turn you down or charge more because of your health history.

Once the window closes, insurers can check your health records and reject you or charge more for pre-existing conditions. Most states have no guaranteed way back in unless you qualify for a special guaranteed issue period, such as after losing employer coverage.

Plan K's savings last only while your health care use stays low. In MoneyGeek's data, a 65-year-old on issue age pricing pays $95 a month for Plan K, vs. $188 for Plan N and $239 for Plan G. That gap disappears once you need more than occasional care.

You don't have to reach Plan K's $8,000 cap for Plan G to become the cheaper plan. At 65 on issue age pricing, Plan K saves $1,726 a year in average premiums. One hospital stay plus $8,584 in Medicare-approved Part B care after the deductible brings your Plan K cost sharing to $1,726, and the saving is gone. Past that point, Plan G costs less for the year.

The national tables show average monthly premiums in MoneyGeek's data for Plans K, L, N and G at ages 65 and 75. Attained age, issue age and community pricing are averaged separately. For each state, the state table gives the range of Plan K premiums at the same two ages. Coverage rules, deductibles and the 2026 out-of-pocket limit come from CMS and Medicare.gov.