The ABN and who actually owes the bill after a Medicare denial
Checked against the current rules on September 24, 2026.
This is where most family cases involving a provider bill after a Medicare denial are actually won or lost — not by re-arguing the medical necessity question, but by showing whether a valid ABN was given.
Source: 42 CFR §§ 411.400-.408 — limitation on liability for a denied service.
Under Section 1879 of the Social Security Act, a family isn't liable for a denied service unless they knew, or could reasonably have been expected to know, that Medicare wouldn't pay for it.42 CFR 411.400
In practice, that knowledge requirement is satisfied by a valid, written Advance Beneficiary Notice (form CMS-R-131) given before the service — one that specifically names the item or service, not a blanket notice covering "whatever Medicare doesn't pay."42 CFR 411.404
Without a valid ABN given first, the provider — not the family — is the one considered to have known the risk, and generally can't collect from the family; a provider who already collected without a valid ABN generally has to refund it.42 CFR 411.408
What makes an ABN valid
A valid ABN has to be given before the service, specifically name it, include a genuine cost estimate, and give the beneficiary a real, unforced choice — not an option already checked for them, and not one sprung on them during an emergency.
A defective ABN — pre-checked, missing a real cost estimate, or given under emergency conditions — doesn't protect the provider's own right to bill, the same as if no ABN had been given at all.
An ABN also has to be current, not just valid
For an ongoing course of treatment, a single ABN only protects the provider for about a year — Medicare's own claims-processing manual requires a fresh, re-signed notice at least annually if the same non-covered item or service continues being furnished.42 CFR 411.404
A stale ABN — one signed well before the dates of service actually being billed — doesn't transfer liability to the family any more than no ABN at all. This is a real, separate argument from whether the service itself was medically necessary, and it's worth checking the date on file against the actual dates being billed.
This distinction shows up in real Medicare Appeals Council decisions, not just the manual text — a provider that kept billing on an old notice, well past the point a fresh one was required, has been held liable for the non-covered charges itself rather than the family it billed.
Sources — last checked September 24, 2026
- 42 CFR 411.400as of September 24, 2026
- 42 CFR 411.404as of September 24, 2026
- 42 CFR 411.408as of September 24, 2026
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By CaseWhy Appeals editorial. See how this content is produced. Not legal advice. Not affiliated with or endorsed by Medicare, CMS, or any health plan. A product of CaseWhy LLC.
