Is the SNF responsible for paying ambulance transportation costs?

The SNF is not responsible for paying the ambulance fees imo.
They do, as a courtesy and routine procedure provide insurance information so that the ambulance company can bill the insurance properly.

When a claim is denied, someone may have used the wrong codes for treatment and diagnosis, and necessity for the ambulance. May require an explanation by treating physicians.

Either the SNF admin or the ER doctor (admin) can provide better information to the insurance company (medicare) to assist in an appeal. You can mail the insurance cards to the ambulance company. You can request an appeal, but the reasoning needs to come from the doctors. So call the billing office of the hospital so they can provide info to the ambulance company.

You will see the reason for the denial on the explanation of benefits. It may be that the charges are not covered at all. Read your EOB, call medicare to find out under what circumstances the charges are covered. Sometimes, the EOB will state if you did not know, you might not have to pay some charges.

If the charges are correct, negotiate with the ambulance company.

When my Dad was on his own, if he was taken by ambulance to the ER and admitted to the hospital Medicare paid for the trip. If he was not admitted my Dad had to pay.
Now he is on on Medicaid and he does not pay. He has no money at all. As long as he doesn’t go over the $2000 amount in his account, Medicaid pays.
Hope that helps.

When Mom was in independent living on Medicare with supplemental insurance, neither paid for her multiple trips to the ER. Medicare doesn’t cover ambulance transport. It was $300 a ride and we made and paid for many trips. Sigh. Now that she’s in NH and on Medicaid, Medicaid pays for transport, and the billing shouldn’t involve you. The only time I ever saw a bill, it was a mistake and I brought it to the NH admin and she said it was a mistake and gave it to accounting to submit to Medicaid.

Your mother is responsible, or rather Medicare should be. My mom, FIL, MIL, have all been in NH and every time they were transported to Dr or hospital Medicare always paid their required portion.

No, she is. I would call the transport service if they coded the claim correctly. I thought Medicare paid for transport.