It’s called "Wall Time" in the industry. Your ambulance arrives at the hospital, but every bed in the ER is full. The paramedics can't leave you on the floor, so they must stay with you on their stretcher in the hallway. Some providers will bill you for this under Code A0420.
The 15-Minute Rule
Wait time is usually billed in 15-minute segments. Importantly, the first 30 minutes of waiting is generally considered part of the "standard transport service" and is NOT billable. Providers can only start the clock for A0420 after that initial 30-minute grace period has passed.
If you were in the hallway for 45 minutes, they might bill you for one 15-minute increment. If you were there for 2 hours, that's six increments, which can add hundreds of dollars to your bill.
How to Dispute
Wait time is almost always considered an "ancillary" fee that insurance companies reject. If you are being billed $200 for "Wait Time," you can argue that you, the patient, had no control over the hospital's staffing levels or the "Transfer of Care" delay. In many states, billing a patient for a hospital's inefficiency is legally questionable.
Practical Advice: If you see A0420 on your bill, ask the hospital for their "ER Intake Timestamp" and compare it to the ambulance crew's "Off-Stretchered" time. If the gap is less than 30 minutes, the charge is fraudulent.