An ABN form, formally called an Advance Beneficiary Notice of Noncoverage (CMS-R-131), is a document that Medicare providers give you before performing a service they believe Medicare will not pay for. It tells you the specific service in question, the estimated cost, and the reason the provider thinks coverage will be denied. You then choose how to proceed, including whether to accept financial responsibility.
The form applies only to people enrolled in Original Medicare (Fee-for-Service). Its core purpose is to make sure you aren’t blindsided by a bill. If a provider fails to give you an ABN before delivering a service that Medicare denies, the provider, not you, is typically stuck with the cost.
When Providers Must Issue an ABN
Providers are required to give you an ABN when they expect Medicare to deny coverage for a service that Medicare normally covers. The most common reason is medical necessity: your provider may believe the test, treatment, or supply is helpful for you personally but doesn’t meet Medicare’s criteria for coverage in your particular situation. For example, Medicare covers routine blood work, but if your provider orders a specific panel more frequently than Medicare guidelines allow, they would need to issue an ABN before drawing the blood.
The ABN must be given before the service is performed. Handing you one after the fact doesn’t count, and in that case the provider generally cannot bill you for a denied claim. Providers who must issue ABNs include physicians, independent labs, skilled nursing facilities, and home health agencies providing outpatient items and services under Medicare Part B.
There is one category where the ABN is not required: services Medicare never covers at all. Things like cosmetic surgery or routine dental care are statutorily excluded from Medicare, meaning they were never a covered benefit in the first place. A provider may still give you a voluntary ABN as a courtesy in those situations, but you are not required to sign it, and it doesn’t change who owes what.
Your Three Options on the Form
The ABN presents three choices. Understanding the differences matters because each one affects both your wallet and your right to appeal.
- Option 1: Get the service and have Medicare billed. You receive the care, and the provider submits the claim to Medicare for an official coverage decision. If Medicare pays, great. If Medicare denies the claim, you are responsible for the cost, but you have the right to appeal that denial. You’ll receive a Medicare Summary Notice explaining the decision and how to file an appeal. The provider can ask you to pay upfront, but if Medicare ultimately does pay, the provider must refund you (minus any copays or deductibles).
- Option 2: Get the service but skip Medicare entirely. You receive the care and agree to pay out of pocket without involving Medicare at all. Because no claim is submitted, there is no denial, which means you cannot appeal. This option makes sense if you’re confident Medicare won’t cover the service and you don’t want to wait on a formal decision.
- Option 3: Decline the service. You choose not to receive the item or service. You owe nothing, and there is nothing to appeal. This is the right choice if the potential out-of-pocket cost isn’t worth it to you.
You must check one option, sign the form, and date it. If you leave the form blank or refuse to sign, the provider can still deliver the service, but the lack of a valid ABN limits the provider’s ability to bill you if Medicare denies coverage.
How Option 1 Appeals Work in Practice
If you pick Option 1, the claim goes through Medicare’s normal processing. You’ll eventually receive a Medicare Summary Notice in the mail (or online if you’ve set that up) showing whether the claim was paid or denied. If denied, the notice includes step-by-step instructions for filing an appeal. The first level of appeal is called a redetermination, where a different Medicare reviewer takes a fresh look at the claim. Many denials, particularly those based on medical necessity, do get overturned on appeal, especially if your provider submits additional documentation supporting why the service was appropriate for you.
Choosing Option 1 is generally the safest route when you aren’t sure whether Medicare will pay. It preserves your appeal rights while still getting you the care you need.
What the ABN Must Include
A valid ABN lists the specific items or services the provider expects Medicare to deny. It cannot be vague or generic. The form must also include an estimated cost so you know the potential financial impact before deciding. Additionally, the provider should include the reason they expect the denial, written in plain language you can understand.
The form itself is standardized by CMS (the federal agency that runs Medicare). Providers cannot create their own version or modify the official layout. The most recent version was approved by the Office of Management and Budget in March 2025, is effective immediately, and expires March 31, 2029. Providers had until May 12, 2026 to transition from the previous version.
What Happens Without a Valid ABN
This is the detail most worth knowing: if a provider delivers a service that Medicare denies and they never gave you a properly executed ABN beforehand, the provider absorbs the cost. They cannot bill you for it. The ABN exists specifically to shift financial liability from the provider to you, and without it, that shift doesn’t happen.
This protection is why timing matters so much. An ABN handed to you after the service, or one that’s missing your signature, or one that doesn’t clearly describe the specific service in question, is considered invalid. In all of those cases, you are generally not liable for the denied charge.
ABN vs. Other Medicare Notices
The ABN is sometimes confused with other Medicare notices, but it serves a distinct role. It applies only to Part B (outpatient) services under Original Medicare. If you’re in a Medicare Advantage plan (Part C), providers use a different form called a Notice of Medicare Non-Coverage or a plan-specific denial letter. If you’re being discharged from an inpatient hospital stay and disagree with the timing, that involves a different notice as well.
The ABN is also not the same as a general financial consent form. Many medical offices ask you to sign a blanket agreement saying you’ll pay for anything insurance doesn’t cover. That’s a separate document. The ABN is specific to a particular service, with a particular estimated cost, for a particular reason Medicare may not pay.