What is an Advance Beneficiary Notice (ABN)? 

A notice that the hospital or doctor gives the patient before the treatment, telling the patient that Medicare will not pay for some treatment or services. The notice is given to the patient so that the patient may decide whether to have the treatment or not, If the patient accepts to take the treatment then they must pay for it. Medicare payer uses the name ABN, and commercial payers other than medicare will use the name WOL, both ABN and WOL forms are the same.