Medicare coinsurance is the share of the medical costs you pay once you’ve reached your Medicare deductible.

Although original Medicare (Part A hospital insurance and Part B medical insurance) covers most of your medical costs, it doesn’t cover everything.

When Medicare pays a percentage of a medical cost, you’re responsible for the remaining percentage. You can either pay that out of your pocket or purchase a Medicare Supplement plan (Medigap plan) to cover all or part of it.

Keep reading to learn more about Medicare coinsurance and how much you pay based on which plans you’re enrolled in.

With Medicare Part A inpatient coinsurance, in 2020 you pay:

  • Days 1 to 60: $0 coinsurance for each benefit period
  • Days 61 to 90: $352 coinsurance per day of each benefit period
  • Days 91 and beyond: $704 coinsurance per each lifetime reserve day after day 90 for each benefit period (up to 60 days over your lifetime)
  • Skilled nursing facility coinsurance: $176

With Medicare Part B, after you meet your deductible ($198 in 2020), you typically pay 20 percent coinsurance of the Medicare-approved amount for most doctor and outpatient services and durable medical equipment.

It’s your first day with original Medicare (Part A and Part B) and you visit your doctor for a $500 outpatient treatment.

Your doctor appointment is covered by Medicare Part B. Your doctor bills Medicare for $500.

In 2020, Part B carries an annual deductible of $198, so you’re responsible for the first $198 worth of Part B-covered services for the year.

After the Part B deductible, the remaining $302 of your bill is covered in part by Medicare and in part by a coinsurance cost covered by you. Your share is 20 percent ($60.40) and Medicare Part B’s share is 80 percent ($241.60).

Your share of the $500 total medical bill is $258.40, broken down as:

  • 2020 Part B deductible: $198
  • 20 percent (of remaining $302) Part B coinsurance: $60.40
  • total you pay: $258.40

On the next $500 bill for the same treatment from the same doctor, you’ll have already paid your Part B deductible, so Medicare will pay 80 percent ($400) and you will pay 20 percent ($100).

Different Medigap plans cover different coinsurance, including:

Plan A and Plan B cover:

  • Part A coinsurance and hospital costs up to 365 days after you’ve used up your Medicare benefits
  • Part A hospice care coinsurance
  • Part B coinsurance

Plan C, Plan D, Plan F, Plan G, Plan M, Plan N cover:

  • Part A coinsurance and hospital costs up to 365 days after you’ve used up your Medicare benefits
  • Part A hospice care coinsurance
  • Part B coinsurance
  • skilled nursing facility care coinsurance

Plan K covers:

  • Part A coinsurance and hospital costs up to 365 days after you’ve used up your Medicare benefits
  • 50 percent of Part A hospice care coinsurance
  • 50 percent of Part B coinsurance
  • skilled nursing facility care coinsurance


Plan L covers:

  • Part A coinsurance and hospital costs up to 365 days after you’ve used up your Medicare benefits
  • 75 percent of Part A hospice care coinsurance
  • 75 percent of Part B coinsurance
  • skilled nursing facility care coinsurance

With original Medicare (parts A & B), once you’ve reached your deductible, Medicare pays a share of the cost of Medicare-approved treatments and you pay a share. Coinsurance is your share of the costs.

You can either pay the coinsurance out of your pocket or purchase a Medicare Supplement plan (Medigap Plan) to cover all or part of it.