How to read a Medicare Summary Notice

If you have Original Medicare, you get a Medicare Summary Notice (MSN) in the mail at least twice a year. It looks a lot like a bill, but it isn't one. It's Medicare's record of what your providers billed, what Medicare paid, and what you may owe. This guide shows you how to read it and how to use it to check your bills. It's part of our guide on how to read a medical bill.

Who gets an MSN, and how often?

People with Original Medicare get an MSN. That means Part A, which is hospital insurance, and Part B, which is medical insurance.

If you have a Medicare Advantage Plan, you don't get an MSN for the care your plan covers. Your plan sends you an explanation of benefits (EOB) instead. It comes each month you fill a prescription, visit a provider, or file a claim. Our guide to EOB vs. medical bill shows how to check one.

As of September 2026, Medicare mails an MSN every 6 months if you got any services or supplies in that time. If Medicare is sending you a payment, you get that notice as the claim is processed.

You can also sign up for electronic MSNs. Then you get an email for any month with a processed claim. In your Medicare.gov account, you can usually see a claim within 24 hours after it's processed.

What's on each page?

An MSN has 4 sections. A Part B notice covers doctors' visits, outpatient care, tests, and other medical care. A Part A notice covers inpatient hospital stays, skilled nursing facility care, hospice, and home health care.

What do the columns mean?

On a Part B notice, each service gets its own line. Here's what the main columns mean.

• Service Approved? Whether Medicare covered the service.
• Amount Provider Charged. The provider's full fee for the service.
• Medicare-Approved Amount. The amount a provider can be paid for the service. It's often less than the charge.
• Amount Medicare Paid. What Medicare paid the provider. It's usually 80% of the approved amount, after your deductible.
• Maximum You May Be Billed. The most the provider is allowed to bill you. It can include your deductible, your coinsurance, and charges Medicare didn't cover.

The last column is the one to compare with your bill. If you have a Medigap policy or other insurance, it may pay all or part of that amount.

A Part A notice for a hospital stay uses slightly different columns. It also shows the benefit days you've used.

What does "assigned" or "unassigned" mean?

A provider who accepts assignment agrees to take the Medicare-approved amount as full payment. They can bill you only for your deductible and coinsurance.

A provider who doesn't accept assignment can charge up to 15% more than the Medicare-approved amount. This cap is called the limiting charge. On these claims, Medicare usually pays you directly, and you pay the provider. Your MSN says whether each claim was assigned or unassigned.

Where do you see your deductible status?

Page 1 shows your deductible information. You pay a yearly deductible before Medicare starts to pay. As of 2026, the Part B deductible is $283. The Part A deductible is $1,736 for each benefit period.

After that, you usually pay 20% of the Medicare-approved amount for Part B care. Early in the year, the deductible can make your share higher than you expect.

Why the MSN and your bill might not match

Your bill and your MSN should match. When they don't, it's often for one of these reasons:

• The bill came before Medicare processed the claim. It may show the full charge, with no Medicare payment.
• The Medicare adjustment is missing. An assigned provider should write off the gap between its charge and the approved amount.
• A payment wasn't posted. Medicare's payment, or one from your Medigap plan, may not be on the bill yet.
• You paid at the visit. If the provider reported your payment, the MSN lowers the Maximum You May Be Billed by that amount. If not, subtract it yourself.
• A service is listed that you didn't get. It could be a mix-up with another patient or a coding mistake.
• Medicare denied the claim. A note on the claims page explains why.

Our guide to why a medical bill is higher than the EOB covers these causes in more detail. The same steps apply to an MSN.

How to check your bill against your MSN

Find the bill and the MSN for the same date of service. Then work through these steps.

1. Match the visit. Check the provider's name, the date, and each service. Make sure you got the care listed.
2. Find the Maximum You May Be Billed. That's the most you should owe for the claim.
3. Subtract what you already paid. Include any copay or deposit you paid at the visit.
4. Compare it with the amount due. If the bill asks for more, call the billing office and ask why.
5. Ask for an itemized statement. You can ask any provider for one, for any service or claim. Our guide on how to get an itemized bill includes a script.

Say Linda's father, Frank, has Original Medicare. He sees a cardiologist on March 10, 2026. The doctor accepts assignment. Frank has already paid $183 toward his $283 Part B deductible, so he has $100 left to meet.

Column	Amount
Amount Provider Charged	$400
Medicare-Approved Amount	$250
Amount Medicare Paid	$120
Maximum You May Be Billed	$130

Here's the math. The first $100 of the approved amount goes to Frank's deductible. That leaves $150. Medicare pays 80% of $150, which is $120. Frank's coinsurance is 20% of $150, which is $30. So the most he can be billed is $100 + $30 = $130.

A month later, the doctor's bill arrives.

Line	Amount
Charges	$400
Medicare payment	−$120
Amount due	$280

The bill is $150 higher than the MSN allows. That's the gap between the $400 charge and the $250 approved amount. An assigned provider can't bill Frank for it.

Linda calls the billing office and asks for a corrected bill of $130.

How to appeal a claim on your MSN

If you disagree with a coverage or payment decision, you can appeal. The first level is called a redetermination.

• Deadline: Medicare must receive your appeal within 120 days from the date you get the MSN. The exact date is printed on the last page.
• How: Circle the items you disagree with on the MSN. Explain why, add any records that help, and mail it to the address on the last page. Or use Medicare's redetermination request form.
• Decision: You'll generally hear back within 60 days after Medicare gets your appeal.

If you miss the deadline, you may still be able to appeal if you have a good reason. For a denied claim, also call the provider, since a missing detail can sometimes be fixed without an appeal.

What if you see care you didn't get?

First, call the provider. It may be a simple mistake, like the wrong date.

If the provider can't explain it, or you think someone is using your Medicare number, call 1-800-MEDICARE (1-800-633-4227). You can also report it online to the Office of Inspector General at the U.S. Department of Health and Human Services.

When to get help

You can often sort out a mismatch yourself with 1 or 2 calls. It's worth getting help when:

• The provider won't correct a bill that's higher than the Maximum You May Be Billed.
• Medicare denied a claim and you're not sure why.
• You're close to the 120-day appeal deadline.
• You're managing a parent's Medicare and need permission to talk with Medicare for them.

Call 1-800-MEDICARE (1-800-633-4227) with questions about a claim. Your State Health Insurance Assistance Program (SHIP) offers free, local Medicare counseling. A medical bill advocate can also take on the calls for you.

If you're handling bills for a parent, our guide to help with elderly parent medical bills covers the permission forms you need.