How to Read Your Parent's Medicare Letter: MSN, EOB & Denials (2026)
By Michelle Harburg, Co-Founder, MediNav · Updated July 2026
That official-looking Medicare letter your parent got may not be a bill at all. A plain-English guide for caregivers to Medicare Summary Notices, Explanations of Benefits, and denial letters, what they mean and what to do.
One of the most stressful moments in helping a parent is a scary-looking Medicare letter with big dollar amounts on it. The good news: many of these are not bills. Here's how to tell what your parent actually received and what, if anything, to do.
The Medicare Summary Notice (MSN), not a bill
If your parent has Original Medicare, every few months they get a Medicare Summary Notice listing the services Medicare was billed for, what Medicare paid, and the 'maximum you may be billed.' That last number scares people, but the MSN is a statement, not a bill. It's for reviewing, check that the services listed actually happened, which is also how you catch fraud.
The Explanation of Benefits (EOB), also not a bill
If your parent has a Medicare Advantage or Part D plan, the equivalent is an Explanation of Benefits from their insurer. Same idea: it shows what was billed and what the plan covered. It is not a request for payment. The actual bill, if there is one, comes separately from the doctor, hospital, or pharmacy.
Denial letters, these need action
A denial letter is different, and time-sensitive. It means Medicare or the plan decided not to cover a service, item, or medication. It will say why, and, importantly, it lists a deadline to appeal, often 60 to 120 days from the date of the notice. If your parent's doctor believes the service is needed, appealing is worth it: a large share of appeals succeed.
'Is this a bill?', a quick test
Look at the top of the document. If it says 'Medicare Summary Notice,' 'Explanation of Benefits,' or 'This is not a bill,' it's a statement to review, not something to pay. If it comes from a provider or pharmacy and asks for payment by a date, it's a bill. If it says a service was 'denied' or 'not covered,' it's a decision you can appeal.
What to do next
For an MSN or EOB, check the services are real and file it. For a bill, make sure the MSN or EOB shows Medicare or the plan already processed it before paying anything. For a denial, note the appeal deadline immediately and gather a note from the doctor. And if a letter is just confusing, you can photograph it and have it explained in plain English in seconds.
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Is a Medicare Summary Notice a bill?
No. A Medicare Summary Notice (MSN) is a statement of what Medicare was billed and paid over the past few months. The 'maximum you may be billed' figure is not a request for payment, the MSN is for reviewing services, not paying them.
My mom got a letter saying a claim was denied, what do I do?
A denial can be appealed, and appeals often succeed. Find the appeal deadline on the letter (usually 60 to 120 days), get a supporting note from her doctor if the service is needed, and file the appeal before the deadline. To handle it for her, you'll want to be her authorized representative using Form CMS-1696.
What's the difference between an MSN and an EOB?
They're the same idea for different coverage. Original Medicare sends a Medicare Summary Notice (MSN); a Medicare Advantage or Part D plan sends an Explanation of Benefits (EOB). Both list what was billed and covered, and neither is a bill.
How long do we have to appeal a Medicare denial?
The deadline is printed on the denial notice and is often 60 to 120 days from the date of the notice, depending on the type of coverage. Don't wait, note it as soon as the letter arrives.
Updated July 2026. Sources: Medicare.gov, SSA, CMS (2026). Estimates, verify with SSA and your state.