The Medicare administrative contractors (MACs) continue to question claims. The zone program integrity contractors (ZPICs) seek pattern errors suggesting fraud and abuse. The recovery audit contractors (RACs) operate under great incentives to find instances of improper payment. The U.S. Department of Health and Human Services HHS) office of Inspector General (OIG) auditors look for questioned costs, and their investigators, along with the U.S. Department of Justice (DOJ), seek patterns suggesting fraudulent billing. All are looking at all facets of claim submissions to detect coding errors and documentation for medical necessity.