Not That Big Four Although "The Big Four" is most commonly known as the four largest global accounting and professional services firms — Deloitte, PwC, EY, and KPMG — today I'm referring to the four most used CPT/HCPCS codes in outpatient therapy. Where This Data Comes From Each year CMS publishes the "Top 200 Level I Current Procedural Terminology/HCPCS Codes Ranked by Services." It ranks the CPT/HCPCS codes most frequently billed to Medicare Part B. Most are surprised to le