If Medicare denies a surgery claim, do I have to pay the surgeon?

Health insuranceWho paysChecked Nov 5, 2026

From K.Actuary, founded by Sangmin Kwon, ASA · sources checked 2026-11-05 · Source: Medicare.gov · Checking the status of a claim View original ↗

In short

It depends on why Medicare said no and whether you were warned in writing first.
Your Medicare Summary Notice shows the most you may owe.
You can appeal within 120 days. If you paid and should not have, ask for money back within 6 months.

What this means

Your Medicare Summary Notice (MSN) shows what Medicare paid and the maximum amount you may owe the provider [1]. Start there.

Did Medicare say the surgery was "not reasonable and necessary"? Then special rules may protect you. Medicare can still pay if the doctor took assignment and neither of you knew, or should have known, that it was not covered [2]. You count as knowing if you got a written notice that it was not covered, for example from the doctor before the surgery [3]. Doctors use a form called an Advance Beneficiary Notice (ABN) to shift possible costs to you when they expect Medicare to say no [4].

Did you already pay? If you did not know it was not covered, and the doctor knew or should have known, Medicare can pay you back. Ask before the end of the sixth month after the month you paid, or the month Medicare told you that you do not owe it, whichever is later [5].

You can also appeal the denial. File the first appeal within 120 days after you get the notice [6].

Your next step

Read the denial reason and "maximum you may be billed" on your MSN. Ask the surgeon's office for a copy of any ABN you signed. Do not pay more than the MSN maximum while you sort it out.

Deadline: appeal within 120 calendar days after you receive the MSN.

Check it yourself

The MSN denial code tells you the reason. These rules cover denials for "not reasonable and necessary" and custodial care; for other denial reasons (for example, a service Medicare never covers), "Don't know yet" from these sources.

Where this comes from (6)

[1] Medicare.gov · Checking the status of a claim · checked 2026-11-05
The MSN is a notice that people with Original Medicare get in the mail. It shows: Part A and Part B-covered services or supplies billed to Medicare What Medicare paid The maximum amount you may owe the provider
[2] eCFR · 42 CFR 411.400 · § 411.400(a) · checked 2026-11-05
Medicare pays for “custodial care” and “services not reasonable and necessary” if the following conditions are met: ( 1 ) The services were funished by a provider or by a practitioner or supplier that had accepted assignment of benefits for those services. ( 2 ) Neither the beneficiary nor the provider, practitioner, or supplier knew, or could reasonably have been expected to know, that the services were excluded fro…
[3] eCFR · 42 CFR 411.404 · § 411.404(b)-(c) · checked 2026-11-05
( 1 ) Written notice is given to the beneficiary, or to someone acting on his or her behalf, that the services were not covered because they did not meet Medicare coverage guidelines. … ( c ) Source of notice. The notice was given by one of the following: … ( 3 ) The provider, practitioner, or supplier that furnished the service.
[4] CMS · FFS ABN · checked 2026-11-05
beneficiaries in situations where Medicare payment is expected to be denied. The ABN is issued in order to transfer potential financial liability to the Medicare beneficiary in certain instances.
[5] eCFR · 42 CFR 411.402 · § 411.402(a) · checked 2026-11-05
( 1 ) The beneficiary paid the provider, practitioner, or supplier some or all of the charges for the excluded services. ( 2 ) The beneficiary did not know and could not reasonably have been expected to know that the services were not covered. ( 3 ) The provider, practitioner, or supplier knew, or could reasonably have been expected to know that the services were not covered. ( 4 ) The beneficiary files a proper requ…
[6] eCFR · 42 CFR 405.942 · § 405.942(a) · checked 2026-11-05
any request for redetermination must be filed within 120 calendar days from the date a party receives the notice of the initial determination.

How we found this

We matched your question to 6 official sources, quoted the exact lines, and re-checked each quote against its source on 2026-11-05.

What we don’t know yet

Your own plan or notice may say something different. If your letter cites another rule, send it and we will look again.

Every answer is checked against the official rule it quotes.

Information only — not legal advice. Your plan, insurer or agency decides.

This answer quotes the official sources listed above, with the date we checked them. Your own policy, notice and state rules control. We are not your lawyer or your insurer. We don’t file, argue or negotiate claims for you — you send any letter or form yourself.

Ask a question Get help with my claim