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MEDICARE BASICS: COMMONLY USED ACRONYMS Target Audience: Medicare Fee-For-Service Program (also known as Original Medicare)
The Hyperlink Table, at the end of this document, provides the complete URL for each hyperlink.

If you interact with Medicare, you probably come across acronyms on a regular basis. It can be difficult to keep track of them all!

This resource lists Medicare-related acronyms. While the list is not all-inclusive, it contains those acronyms you may encounter in Medicare and Medicare Learning Network® (MLN) products.

What Is an Acronym?
An acronym is a word formed from the initial letters or parts of a name or title.

Want more information about Medicare? Watch this 5-minute Centers for Medicare & Medicaid Services (CMS) “What Is Medicare?” video for a high-level overview of the Medicare Program, including basic information about Medicare’s various parts and who it covers.


  • ABD: Aged, Blind, and Disabled

  • ACH: Automated Clearing House

  • ACP: Advance Care Planning

  • AHA: American Hospital Association

  • AHRQ: Agency for Healthcare Research and Quality

  • ALJ: Administrative Law Judge

  • AMA: American Medical Association

  • ANSI: American National Standards Institute

  • AO: Accreditation Organization

  • APA: American Pharmaceutical Association

  • APA: American Psychiatric Association

  • ASC: Accredited Standards Committee

  • AWP: Average Wholesale Price


  • BBA: Balanced Budget Act of 1997

  • BHI: Behavioral Health Integration

  • BHO: Behavioral Health Organization


  • CAL: Coding Analysis for Labs

  • CARC: Claims Adjustment Reason Code

  • CAT: Computerized Axial Tomography

  • CCN: Claim Control Number

  • CE: Continuing Education

  • CEUs: Continuing Education Units

  • CF: Conversion Factor

  • CFC: Conditions for Coverage

  • CFR: Code of Federal Regulations

  • CME: Continuing Medical Education

  • CMN: Certificate of Medical Necessity

  • CMP: Civil Monetary Penalty

  • CMSCE: Centers for Medicare & Medicaid Services Continuing Education Program

  • COBRA: Consolidated Omnibus Budget Reconciliation Act

  • COP: Conditions of Participation

  • COPD: Chronic Obstructive Pulmonary Disease

  • CPAP: Continuous Positive Airway Pressure

  • CPI: Consumer Price Index

  • CR: Change Request

  • CWF: Common Working File


  • DBA: Doing Business As

  • DCN: Document Control Number

  • DDE: Direct Data Entry

  • DEA: Drug Enforcement Administration

  • DOB: Date of Birth

  • DOD: Date of Death

  • DOE: Date of Entitlement

  • DOJ: U.S. Department of Justice

  • DOS: Date of Service

  • DUA: Data Use Agreement

  • DUR: Drug Utilization Review

  • DV: Data Validation

  • DX: Diagnosis


  • ED: Emergency Department

  • EDI: Electronic Data Interchange

  • EFT: Electronic Funds Transfer

  • EGHP: Employer Group Health Plan

  • EIN: Employer Identification Number

  • EMT: Emergency Medical Technician

  • EOB: Explanation of Benefits

  • EOC: Episode of Care

  • EP: Eligible Professional

  • ER: Emergency Room

  • eRx: Electronic Prescribing


  • FAQ: Frequently Asked Question

  • FAR: Federal Acquisition Regulations

  • FCBC: Fingerprint-Based Criminal Background Check

  • FID: Fraud Investigation Database

  • FISS: Fiscal Intermediary Standard (or Shared) System

  • FL: Form/Field Location

  • FOIA: Freedom of Information Act

  • FPS: Fraud Prevention System

  • FWA: Fraud, Waste, and Abuse

  • FY: Fiscal Year


  • GHP: Group Health Plan

  • GPCI: Geographic Practice Cost Index


  • HETS: Health Insurance Portability and Accountability Act (HIPAA) Eligibility Transaction System

  • HH: Home Health

  • HICN: Health Insurance Claim Number (Medicare Number)

  • HIPAA: Health Insurance Portability and Accountability Act of 1996

  • HIPPS: Health Insurance Prospective Payment System

  • HIV: Human Immunodeficiency Virus

  • HMO: Health Maintenance Organization

  • HSA: Health Savings Account

  • HUB Zone: Historically Underutilized Business Zone


  • IACS: Individuals Authorized to Access CMS Computer Services

  • IADL: Instrumental Activities of Daily Living

  • IBT: Intensive Behavioral Therapy

  • IDE: Investigational Device Exemption

  • IDTF: Independent Diagnostic Testing Facility

  • IHS: Indian Health Services

  • IME: Indirect Medical Education


  • For a list of Medicare-related acronyms that start with the letter J, visit the CMS Acronyms webpage.


  • For a list of Medicare-related acronyms that start with the letter K, visit the CMS Acronyms webpage.


  • LIDOS: Line Item Date of Service

  • LOC: Level of Care

  • LOS: Length of Stay

  • LPN: Licensed Practical Nurse


  • MACRA: Medicare Access and CHIP Reauthorization Act

  • MAO: Medicare Advantage Organization

  • MCE: Medicare Code Editor

  • MCP: Managed Care Plan

  • MDH: Medicare Dependent Hospital

  • MEDIGAP: Medicare Gap (Medicare complementary insurance program)

  • MEDPAC: Medicare Payment Advisory Commission

  • MIPPA: Medicare Improvements for Patients and Providers Act

  • MIPS: Merit-Based Incentive Payment System

  • MMA: Medicare Modernization Act

  • MOC: Maintenance of Certification

  • MOON: Medicare Outpatient Observation Notice

  • MQSA: Mammography Quality Standards Act

  • MSA: Medical Savings Account

  • MSN: Medicare Summary Notice


  • NABP: National Association of Boards of Pharmacy

  • NP: Nurse Practitioner

  • NQF: National Quality Forum

  • NUCC: National Uniform Claim Committee


  • OIG: Office of Inspector General

  • OPT: Outpatient Physical Therapy

  • OTAF: Obligated to Accept as Payment in Full


  • PA: Physician Assistant

  • PACE: Program of All-Inclusive Care for the Elderly

  • PAP: Positive Airway Pressure

  • PFFS: Private Fee-For-Service

  • PHI: Protected Health Information

  • PIN: Personal/Provider Identification Number

  • POC: Plan of Care

  • POS: Place of Service

  • PPO: Preferred Provider Organization

  • PPPS: Personalized Prevention Plan Services

  • PT: Physical Therapy

  • PTAN: Provider Transaction Access Number



  • RA: Remittance Advice

  • RAP: Request for Anticipated Payment

  • RARC: Remittance Advice Remark Code

  • RN: Registered Nurse

  • RNHCI: Religious Nonmedical Health Care Institution

  • RRB: Railroad Retirement Board

  • RTP: Return to Provider

  • RVU: Relative Value Unit


  • SA: State Survey Agency

  • SAMHSA: Substance Abuse and Mental Health Services Administration

  • SCH: Sole Community Hospital

  • SCHIP: State Children’s Health Insurance Program

  • SLP: Speech Language Pathologist/Pathology

  • SME: Subject Matter Expert

  • SNP: Special Needs Plan

  • SOM: State Operations Manual

  • SSA: Social Security Act

  • SSN: Social Security Number



  • For a list of Medicare-related acronyms that start with the letter U, visit the CMS Acronyms webpage.


  • For a list of Medicare-related acronyms that start with the letter V, visit the CMS Acronyms webpage.


  • WA: Working Aged

  • WBT: Web-Based Training

  • WEDI: Workgroup for Electronic Data Interchange


  • For a list of Medicare-related acronyms that start with the letter X, visit the CMS Acronyms webpage.


  • YTD: Year to Date



For a complete list of Medicare-related acronyms, visit the CMS Acronyms webpage.

For a glossary of terms, visit the CMS Glossary.

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