I certainly hope you never need an ambulance, but at some point you may have to take one during a medical emergency.

If you have Original Medicare, your Part B (medical insurance) covers ambulance services to or from a hospital, critical-access hospital, or skilled nursing facility only when other transportation could endanger your health.

In some cases, Medicare may cover ambulance services from your home or a medical facility to get care for a health condition that requires you to be transported only by ambulance. Medicare may also cover ambulance services to or from a dialysis facility if you have End-Stage Renal Disease and other transportation could jeopardize your health.

Emergency ambulance transportation is provided after you’ve had a sudden medical emergency and every second counts to prevent your health from getting worse. Here are some examples of when Medicare might cover emergency ambulance transportation:

* You’re in severe pain, bleeding, in shock, or unconscious;

* You need oxygen or other skilled medical treatment during transportation.

Medicare will only cover ambulance services to the nearest appropriate medical facility that’s able to give you the care you need. If you choose to be transported to a facility farther away, Medicare’s payment will be based on the charge to the closest appropriate facility. If no local facilities are able to give you the care you need, Medicare will help pay for transportation to the nearest facility outside your local area that’s able to give you the care you need.

Medicare may pay for an air ambulance (airplane or helicopter) if your condition requires immediate and rapid transportation that a ground carrier can’t provide, and your pickup location is either: 1) hard to get to by ground transportation; or 2) long distances or heavy traffic could keep you from getting care quickly.

Non-emergency ambulance transportation may be covered when you need it to diagnose or treat your condition and any other mode of transportation could endanger your health.

In some cases, Medicare covers limited non-emergency ambulance transportation if you have a statement from your doctor or other care provider stating that ambulance transportation is necessary due to your medical condition. For example, Medicare may cover a non-emergency ambulance for people confined to bed if other types of transport could endanger their health.

If the ambulance company believes Medicare may not pay for non-emergency service because it isn’t medically necessary or reasonable, they must give you an Advance Beneficiary Notice (ABN).

The ABN has option boxes that allow you to choose whether you want the service and explains your responsibility to pay for it. If you indicate that you’ll pay for the service and sign the ABN, you’re responsible for paying if Medicare doesn’t. You may be asked to pay at the time of service.

If you’re in a situation that requires an ambulance company to give you an ABN and you refuse to sign it, the company will decide whether to take you by ambulance. If the company decides to send you in an ambulance even though you refused to sign, you may still be responsible for paying for the trip if Medicare doesn’t pay.

You won’t be asked to sign an ABN in an emergency situation.

You can appeal if Medicare doesn’t pay for the ambulance trip and you believe it should have.

If Medicare covers your trip, it will pay 80% of the Medicare-approved amount after you’ve met the Part B deductible ($147 in 2013). You pay the remaining 20%.

How do you know if Medicare didn’t pay for your ambulance? You’ll get a Medicare Summary Notice explaining why Medicare didn’t pay.

David Sayen is Medicare’s regional administrator for Arizona, California, Nevada, Hawaii, and the Pacific Territories. You can always get answers to your Medicare questions by calling 1-800-MEDICARE (1-800-633-4227).