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

Medicare Supplement Plan K is a private insurance policy that helps pay the costs Original Medicare leaves behind. Original Medicare covers hospital care under Part A and doctor visits under Part B. It still leaves you responsible for deductibles and co-insurance fees.    

What separates Plan K from the nine other standardized Medigap plans is an annual spending cap set at $8,000 in 2026. Only Plan K and Plan L include this feature. Once you reach the cap, the plan covers 100% of eligible costs through the end of the calendar year.   

My analysis of Plan K rates shows the $8,000 cap matters most in years with serious illness or extended inpatient care. Enrollees who rarely use Medicare benefit most from the lower premium. Those with regular specialist visits or frequent hospitalizations pay less overall with Plan G, based on MoneyGeek's cost comparison data.

Medicare Supplement Plan K premiums start at $95 per month for a 65-year-old using issue age pricing, the method that locks your premium based on your age at enrollment rather than your age at renewal. 

MoneyGeek's data shows Plan K premiums converge from $137 to $140 per month by age 75 across all three pricing structures. Issue age pricing starts lowest at $95 at 65 and produces the lowest cumulative cost for policyholders who hold the plan for ten or more years.

In 2026, Plan K premiums vary by more than $1,600 per year across states. A 65-year-old in Utah can find plans starting at $66 per month. A 65-year-old in New York pays $162 flat. Where you live is the largest cost factor after your age.   

Seven states, such as New York, Vermont and Maine, offer only community-rated Plan K policies. Under community rating, your premium doesn't increase as you age. Enrollment at age 65 still matters for guaranteed access to coverage. The price you lock in at 65 is the same one a 75-year-old pays in those states.

*Arkansas, Connecticut, Idaho, Maine, New York, Vermont and Washington show one figure for both ages because they offer only Community-Rated plans. Premiums don't change with age under community rating. Florida, Georgia, Missouri and New Hampshire show one figure per age because they offer only Issue-Age pricing, per the CMS data.

Plan K covers Part A hospital co-insurance in full and pays for an additional 365 days of hospital care after Medicare benefits are exhausted. The plan covers half of all other covered costs, which includes the Part A deductible and Part B co-insurance.

Hospital co-insurance is fully covered because those costs grow fast during a long inpatient stay. Half-covered items add up during years with frequent care. Once you hit $8,000, the plan covers 100% of eligible costs through the end of that calendar year.

Plan K excludes three cost categories. The Part B deductible hasn't been covered by any Medigap plan sold to new Medicare enrollees since 2020. Plan G and Plan N cover excess charges from providers who bill above Medicare-approved rates. Both plans also cover emergency care outside the U.S., which Plan K doesn't.

• Part B deductible: The full 2026 Part B deductible of $283 applies before Plan K benefits take effect on Part B costs, per CMS.
• Part B excess charges: Plan K doesn't cover excess charges when a provider doesn't accept Medicare assignment and bills up to 15% above the Medicare-approved amount.
• Foreign travel emergency: Plan K excludes emergency care outside the U.S.

The choice between these plans comes down to how often you use Medicare and how much you're willing to pay each month. Plan K and Plan L are the only two plans with an annual spending cap. Plans G and N have no cap and cover nearly everything, at a higher monthly premium. 

Plan K's $8,000 cap is higher than Plan L's $4,000, so Plan L limits annual spending more tightly. Plan L also covers three-quarters of most Medicare costs rather than half, which accounts for its higher premium. Plan F was the only plan that covered the Part B deductible but isn't available to enrollees first eligible for Medicare on or after January 1, 2020.

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

Your six-month Medigap open enrollment window is the only period when insurers can't deny coverage or charge more based on your health history. It starts the first day of the month you turn 65 and are enrolled in Part B, per Medicare.gov.   

After that window closes, insurers can review your health records and either reject your application or charge higher premiums based on pre-existing conditions. In most states, there's no guaranteed path back in unless you qualify for a special guaranteed issue period, such as losing employer-sponsored coverage.

Plan K costs less per month than most Medigap plans for Medicare enrollees who use medical services infrequently. At $95 per month at 65, it costs less than Plan G and Plan N upfront. Those savings reverse quickly once you need more than occasional care.   

My analysis shows enrollees who see specialists regularly or have even one inpatient hospital stay can approach the $8,000 cap within a single calendar year. For those enrollees, Plan G's higher premium produces lower total annual costs, based on MoneyGeek's cost comparison across both plans.