"Maximum You May Be Billed" on your Medicare Summary Notice (MSN) is the most a provider can legally charge you for that service after Medicare processes the claim. It usually equals your Part B deductible and 20% coinsurance, plus any denied charges, and it's counted before your Medigap or other insurance pays. If a bill asks for more than this number, call the provider and ask why.
Where do I find "Maximum You May Be Billed" on my MSN?
It shows up in two places. On page 1, there's a summary line called "Total You May Be Billed," which adds up every claim on the notice. On the claims pages, each service has its own "Maximum You May Be Billed" column, to the right of "Amount Medicare Paid."
Medicare's sample Part B MSN shows an eye exam with these numbers:
- Amount provider charged: $143.00
- Medicare-approved amount: $107.97
- Amount Medicare paid: $86.38
- Maximum you may be billed: $21.59
The $21.59 is 20% of the $107.97 approved amount. The same sample shows a second service that was denied: the provider charged $68.56, Medicare paid $0, and the maximum you may be billed was the full $68.56.
How does Medicare figure out the maximum I can be billed?
For most Part B services, the number comes from three pieces:
- Any part of your yearly Part B deductible that was applied to this claim. The 2026 Part B deductible is $283, according to Medicare's 2026 cost sheet.
- Your coinsurance, usually 20% of the Medicare-approved amount after the deductible.
- Charges for denied services, if Medicare didn't cover them.
If your provider does not accept assignment, the maximum can also include an extra amount called the limiting charge (explained below).
Why is my bill different from the "Maximum You May Be Billed" amount?
There are a few common, harmless reasons, and a few that need a phone call.
Reasons a bill may be lower:
- Your Medigap plan, retiree plan, or Medicaid paid part or all of your share. The MSN shows your share before other coverage pays. Look for a note saying the claim was sent to your supplement insurer.
- You already paid a copay at the visit.
Reasons a bill may be higher, worth questioning:
- The bill shows the full "amount provider charged" instead of the Medicare-approved amount.
- The office billed you before Medicare finished processing the claim.
- The bill includes a service that doesn't appear on your MSN at all.
- A charge was applied twice.
If your bill is higher than the maximum, ask the billing office to explain each dollar above it.
Can a doctor ever bill me more than the Medicare-approved amount?
It depends on the doctor's relationship with Medicare.
Providers who accept assignment agree to take the Medicare-approved amount as full payment. Medicare.gov says they agree to charge you only the Medicare deductible and coinsurance.
Non-participating providers don't always accept assignment. Medicare.gov says they can charge more than the approved amount, but in many cases no more than 15% above the amount Medicare approves for non-participating providers. That cap is called the limiting charge. If you see one of these providers, your maximum may include that extra amount.
Providers who opted out of Medicare work under private contracts, and Medicare doesn't pay them at all except in emergencies. Your MSN generally won't show those services, because no Medicare claim is processed.