Mileage billing in EMS is governed by the "Loaded Mile" Rule. From a billing perspective, the odometer only starts running the second the patient is secured in the back and ends the second they are offloaded at the hospital.
No "Deadhead" Miles
An ambulance service may drive 20 miles to reach your house. They are legally prohibited from charging you for that 20-mile trip. If your bill lists 25 miles, but the hospital is only 5 miles from your house, the provider is likely committing "mileage padding" by including their travel time to get to you.
Odometer vs. Air Miles
For Ground Ambulances, miles must be calculated using the odometer reading (whole miles) or specialized mapping software. They cannot charge you for "as the crow flies" distance if the actual road path was different, though they are expected to take the most direct route possible.
Total Miles vs. Partial Miles
CMS rules require providers to round their total loaded mileage up to the next whole mile. If your trip was 5.2 miles, they are allowed to bill for 6 miles. However, they are NOT allowed to use GPS "route optimization" to bill for a longer, circuitous route simply to increase the mileage fee.
Verification Tool: Put your home address and the hospital address into Google Maps. If the maps "Fastest Route" says 4 miles and your bill says 9 miles, you are likely a victim of mileage padding.