ABN (Advance Beneficiary Notice) rules for Medicare billing
An ABN is the Advance Beneficiary Notice of Noncoverage, form CMS-R-131. You give it to an Original Medicare patient before a service Medicare is expected to deny, and a valid signed copy lets you bill the patient if Medicare does deny. It is never required in an emergency, and it does not apply to Medicare Advantage.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: the ABN is the one CMS form that moves financial liability from you to a Medicare fee-for-service patient, and only when it is delivered before the service, completed in full and signed. Without a valid notice you carry the denial and must refund anything you collected. Claims then show the result with modifier GA or GZ.
What is an ABN and who uses it?
The Advance Beneficiary Notice of Noncoverage (ABN), Form CMS-R-131, is issued to Original Medicare fee-for-service patients in situations where Medicare payment is expected to be denied. CMS says its purpose is to transfer potential financial liability to the patient in certain instances.
Physicians, practitioners, suppliers, independent laboratories and outpatient hospitals paid under Part B must use it, as must hospices, home health agencies and religious nonmedical health care institutions. Inpatient hospitals and skilled nursing facilities use the ABN for Part B items and services only.
Claims Processing Manual chapter 30, section 50.1, says the ABN is not used for Medicare Advantage or for Part D drugs. Skilled nursing facilities issue form CMS-10055, the SNF ABN, for Part A stays.
When is an ABN required?
An ABN is required when Medicare is expected to deny a service that is usually covered and you want the option of billing the patient. Section 50.2 of chapter 30 lists the denial reasons that make the notice mandatory:
| Denial reason | Authority named in section 50.2 |
|---|---|
| Not reasonable and necessary, including experimental or research-only tests | Social Security Act 1862(a)(1) |
| Custodial care | Social Security Act 1862(a)(9) |
| Hospice patient who is not terminally ill | Social Security Act 1879(g)(2) |
| Home health: patient not confined to the home, or no need for intermittent skilled nursing | Social Security Act 1879(g)(1) |
| Personalized prevention plan services done more often than coverage guidelines allow | Social Security Act 1862(a)(1)(P) |
| Equipment and supplies: unsolicited telephone contact, supplier number rules, items denied in advance | Social Security Act 1834(a)(17)(B), 1834(j)(1), 1834(a)(15) |
| Non-contract supplier of a competitive bidding item | 42 CFR 414.408(e)(3)(ii) |
For items Medicare never covers, such as routine eye care, dental care and routine foot care, the ABN is optional. Section 50.2.1 says CMS strongly encourages it as a courtesy, and in that use the patient is not asked to choose an option box or sign.
It also cannot shift liability when Medicare pays in full through a bundled payment (section 50.9).
What events trigger an ABN?
Section 50.4 names three: initiations, reductions and terminations. You do not issue a notice every time care is reduced.
- Initiation: the start of a new encounter, plan of care or treatment
- Reduction: a decrease in frequency or duration. The ABN goes out before delivery only if the patient wants care that is no longer reasonable and necessary
- Termination: discontinuing an item or service. The ABN is issued only if the patient wants to continue care that is no longer reasonable and necessary
An LCD or NCD that limits a service by diagnosis, frequency or site is the usual reason you expect denial, so make the ABN decision part of the same coverage check.
How do you complete the ABN form?
Complete every blank before the patient signs. The CMS form instructions (OMB number 0938-0566) require the notice to fit on one page, letter or legal size, and the signature line cannot be filled in ahead of the rest.
| Part of the form | What goes there | What breaks it |
|---|---|---|
| Header | Your name, address and phone number (and TTY if needed), top right | Omitting it. If biller and notifier differ, name both |
| Identification number | Optional internal number such as a medical record number | Putting the MBI or a Social Security number on the form |
| Item, test, service or care | Specific names of what you expect Medicare to deny, with frequency or duration for repeat care | Vague entries on a reduction |
| Reason Medicare may not pay | A plain-language reason for every listed item | A line with no reason |
| Estimated cost | A good faith estimate for every item | Leaving it blank (write that no estimate is available if true) |
| Options box | The patient checks one box | The notifier pre-selecting an option |
| Signature and date | Patient or representative signs and dates | Signing before the rest is complete |
Use the current English or Spanish version. Section 50.5 says the notice is effective by its OMB approval date and approvals normally run three years.
What do the three option boxes mean?
| Option | Patient's choice | What you do | Appeal rights |
|---|---|---|---|
| Option 1 | Wants the service, and Medicare billed for an official decision | Bill Medicare. The result comes back on a Medicare Summary Notice | Yes, per the MSN |
| Option 2 | Wants the service, no bill to Medicare, patient pays | File no claim | None |
| Option 3 | Does not want the service | Do not provide it. Patient owes nothing | None |
Only the patient or representative chooses. If the patient wants some listed services but not others, use more than one ABN. If the patient will not choose, annotate "patient refused to choose an option." If the patient changes their mind after signing, annotate the original with the new choice, signature and date, and revise or cancel any claim already filed.
For a patient with Medicare and Medicaid, the instructions say to have the patient check Option 1 so a claim reaches Medicare. You then cannot bill that patient until both programs have adjudicated. A supplier that does not accept assignment strikes the last sentence of Option 1 and adds the CMS-approved unassigned claim statement.
Can you use an ABN in an emergency?
No. The CMS instructions say ABNs are never required in emergency situations. Section 40.3 of chapter 30 adds that a notice given in a medical emergency or under great duress is treated as invalid.
For hospitals, section 40.4 ties this to EMTALA. Do not give a notice until the medical screening examination is done or an emergency condition is stabilized. After that, a notice may go to the patient only if there is a genuine reason to expect Medicare to deny a specific item or service.
How does the ABN show up on the claim?
A provider may indicate a valid ABN with occurrence code 32 or the applicable HCPCS modifier on contractor claims, and the contractor then holds the patient, not you, liable for the denied charges. If the notice proves invalid, the contractor overrides the GA modifier and finds you liable.
Modifier GA says a signed ABN is on file. Modifier GZ says there is none and a denial is expected. Those pages cover line-level mechanics and denial codes, so this page does not repeat them.
You do not attach the ABN to the claim. Section 110.5.1 says routine copies are not required, but a contractor can ask for them and you must then send them.
How long is an ABN good for, and how long do you keep it?
An ABN stays effective after valid delivery while the care described, the patient's health status and the Medicare coverage guidelines stay the same. If any changes, issue a new one. For repetitive or continuous care, section 50.8 lets you issue another after one year. It cannot be backdated to cover care already given.
Section 50.7 says retention is, in general, 5 years from discharge or completion of delivery of care when no other requirement applies under state law. Scanning the signed paper copy is acceptable, and the entity that bills Medicare should get a copy if it is not the notifier.
What happens when the ABN is missing or defective?
You are likely liable. Section 50.9 says a notifier is likely liable if it knew or should have known Medicare would not pay and did not issue a required ABN, or issued a defective one. You cannot collect from the patient and must promptly refund anything collected.
Section 50.15.3 sets the refund clock. Refund within 30 days after you receive the remittance advice if you do not request review. If you request review within 30 days of the initial determination notice, refund within 15 days after you receive the review determination. Knowing and willful failure can bring civil money penalties and exclusion.
You can still be protected by showing you did not know and could not reasonably have been expected to know that Medicare would not pay (section 50.9). Both patient and provider can appeal the coverage and liability decisions (section 30.3), and Medicare appeal levels covers the path. If this is a pattern, our denial management team can help.
What does an ABN look like in a real claim?
Illustrative numbers only. A Medicare fee-for-service patient is ordered a lab test that Medicare allows once a year, and the patient had it eight months ago. Staff complete an ABN before the specimen is collected.
Without the form the line would carry GZ, the denial would fall on the provider, and any $40.00 taken at the desk would be refunded within 30 days of the remittance advice.
- Advance Beneficiary Notice of Noncoverage (ABN), Form CMS-R-131 · CMS
- ABN form instructions · CMS
- Medicare Claims Processing Manual, Chapter 30 (sections 20 to 50 and 110.5) · CMS
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Common questions
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01What is an ABN?
An ABN is the Advance Beneficiary Notice of Noncoverage, Form CMS-R-131. A provider gives it to an Original Medicare patient before a service Medicare is expected to deny. It tells the patient they may have to pay and lets the provider bill them if the denial happens and the notice was valid.
02When is an ABN required?
It is required when Medicare is expected to deny a usually covered service as not reasonable and necessary, as custodial care, or under the other reasons in Claims Processing Manual chapter 30, section 50.2. For care Medicare never covers it is optional. It is never required in an emergency.
03What is the difference between modifiers GA and GZ?
GA means a valid signed ABN was obtained, so the patient is liable if Medicare denies. GZ means no signed ABN exists and a denial is expected, so the provider is liable. Each modifier has its own page, linked above, with denial codes and claim examples.
04Can an ABN be used in the emergency department?
Not before the medical screening exam and stabilization. CMS says ABNs are never required in emergencies, and manual section 40.4 bars notices before EMTALA duties are met. Afterward, one may be given only when there is a genuine reason to expect Medicare to deny a specific item or service.
05How long must an ABN be kept?
In general, 5 years from discharge or completion of delivery of care, when no other requirement applies under state law (manual section 50.7). A scanned copy of the signed paper form is acceptable. If another entity bills Medicare, give it a copy of the signed ABN.
06Can a patient be billed if the ABN was not signed?
Generally no. If the notice was required and was missing or defective, the provider is likely liable, cannot collect from the patient, and must refund anything collected. The provider can avoid liability only by showing it did not know and could not reasonably have been expected to know Medicare would not pay.
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