The HHS Office of Inspector General's (OIG's) latest update to the 2017 Work Plan includes a review of psychotherapy services billed to Medicare Part B. On the detail page for the new item, the OIG explains:
"In calendar year 2016, Part B allowed approximately $1.2 billion for psychotherapy services, including individual and group therapy. A prior OIG review found that Medicare allowed $185 million in inappropriate outpatient mental health services, including psychotherapy services. The review found that psychotherapy services were particularly problematic, noting that almost half of the psychotherapy services reviewed were inappropriate. Specifically, Medicare paid for services that were not covered, inadequately documented, or medically unnecessary."
Depending on the time period the audit focuses on, the OIG may find even more errors due to confusion about how to report the services. The codes were completely revamped in 2013, with additional revisions in 2017.