A Medicare ABN is an Advance Beneficiary Notice of Non-Coverage. This is a written notice from your medical provider or supplier when they think Medicare might not pay for certain items or services. It's provided to people who have Original Medicare. Those with Medicare Advantage or other health care plans may receive different types of noncoverage notices.

When you get an ABN, you're required to say how you'd like to proceed — or not proceed — with the services and sign the notice. If the ABN isn't signed, your provider can't bill you for the items or services not covered by Medicare and generally won't provide the care outlined.

Here's what you should know about Medicare ABNs.

What does it mean if you get a Medicare ABN?
A Medicare ABN means there's a good chance Medicare won't cover the thing or the service you're trying to have covered. It's an advance notice that you might owe more money than you expect, and you must sign the form if you wish to proceed with services anyway. 

When you receive an ABN, you'll be asked to select one of a few options and sign, saying you understand the terms. These options include: 

Pay first and submit a claim. If you still want the service or the item, you may have to pay out of pocket, and you can have the provider submit a claim to Medicare. If Medicare still doesn't cover it, you can appeal, although you may ultimately owe the balance in full. 

Pay first and don't submit a claim. If you still want the service or the item, you may have to pay out of pocket, and you can choose not to have your provider submit a claim. There is no way to file an appeal in this process.

Refuse the item or service. You can also choose not to get the service or item that Medicare might not cover, and you won't owe anything. No claims are submitted to Medicare.

Does a Medicare ABN mean Medicare won't pay?
No. An ABN is just a notice from a health care provider or supplier that they believe Medicare won't pay for something you seek. It's not an official notice from Medicare. If a claim is filed and Medicare won't cover it, you can file an appeal. 

But if you proceed with an item or service after signing an ABN, you could ultimately be responsible for all charges. 

Will I get an ABN if I have Medicare Advantage?
No. Providers and suppliers can only give an ABN to members who have Original Medicare. Those with Medicare Advantage plans may receive a different kind of notice from providers if a service isn't covered or no notice if their plan paperwork clearly doesn't cover that service. 

What kinds of ABNs are out there?
There's more than one kind of ABN, and several abbreviations are involved. Here's what you might see, depending on the situation.

Home Health Agency Advance Beneficiary Notice: You might get an ABN from a home health agency — which provides health services to people in their homes — if the items and services you'd receive aren't considered medically necessary, the only care you need is non-skilled care or you aren't homebound, among other things.

Home Health Change of Care Notice, or HHCCN: You might get an ABN or an HHCCN from a home health agency when they reduce or halt services due to a business decision on the part of the agency or because your doctor changed your home health prescription. 

Notice of Medicare Non-Coverage, or NOMNC: You should get a NOMNC from your home health agency at least two days before covered services end. This notice provides the date when your covered services will end and how to appeal if you'd like services to continue.

Detailed Explanation of Non-Coverage, or DENC: If you think your services are ending too early, you can appeal your NOMNC and request a review of your case from the Beneficiary and Family Centered Care Quality Improvement Organization, or BFCC-QIO. Your home health agency will then provide a DENC that explains why they think Medicare won't cover your services any longer.

Hospital-Issued Notice of Non-coverage, or HINN: You may get a HINN from a hospital if it believes Medicare may not pay for any part of your Part A inpatient hospital care. This notice will explain why the hospital thinks Medicare won't cover your services and what it would cost you to pay out of pocket. 

» MORE: Read more about Part A coverage of hospital stays

About the author: Kate Ashford is a certified senior advisor (CSA)® and personal finance writer at NerdWallet specializing in Medicare and retirement topics. Read more