The HSD Reference File Explained: What It Is and How MA Plans Use It

What Is the HSD Reference File?

The Health Service Delivery (HSD) Reference File is published annually by CMS as part of the Medicare Advantage and Part D application process. It defines the maximum allowable time-and-distance thresholds for each of the 22 required provider specialty categories, broken down by county and county classification (urban, suburban, rural).

Every Medicare Advantage organization filing a network adequacy submission uses the HSD Reference File as the basis for its analysis. A county-specialty pair is "adequate" if the plan can demonstrate that a sufficient number of providers of that specialty are located within the threshold time and distance for that county's classification.

What the HSD Reference File Contains

The file is published as a series of Excel workbooks available through the CMS Health Plan Management System (HPMS). It contains:

• County-level classification data: Every U.S. county is classified as urban, suburban, or rural based on CBSA population thresholds and RUCA codes for non-CBSA counties
• Specialty-level thresholds: For each of the 22 HSD specialty categories, the file specifies maximum miles and maximum minutes for each county classification
• Provider type requirements: Minimum provider counts required per specialty per county (typically at least two providers per county to avoid single-point-of-failure adequacy)
• Telehealth modifiers: Beginning with the 2024 benefit year, certain specialty categories include telehealth-eligible designations that affect how adequacy is calculated

The 22 HSD Specialty Categories

CMS requires Medicare Advantage plans to demonstrate adequacy across 22 specialty categories. These span primary care, specialists, mental and behavioral health, and ancillary services. Key categories include:

• Primary Care Physicians (PCPs)
• Cardiology
• Dermatology
• Endocrinology
• Gastroenterology
• Hematology/Oncology
• Infectious Disease
• Mental Health (outpatient)
• Neurology
• Nephrology
• OB/GYN
• Ophthalmology
• Orthopedic Surgery
• Otolaryngology (ENT)
• Physical Therapy
• Podiatry
• Pulmonology
• Rheumatology
• Urology
• Skilled Nursing Facility (SNF)
• Home Health
• Pharmacy

How CMS Updates the File Annually

The HSD Reference File is updated each October as part of the annual MA bid cycle. Updates typically include:

• Revised county classifications reflecting updated census data
• Threshold adjustments for specific specialty-county combinations where CMS has identified access gaps in the prior year
• Addition or removal of specialty categories as CMS refines its adequacy framework
• Changes to the telehealth eligibility list

Plans that do not update their adequacy models to reflect the current benefit year's HSD Reference File will submit analyses against outdated thresholds — a filing error that CMS identifies during review and that triggers a deficiency notice.

How Blueprint Loads the HSD Reference File

Blueprint pre-loads the current benefit year's HSD Reference File thresholds for every state as part of the onboarding process. During Day 1 of onboarding, your Blueprint specialist confirms your state, LOB, and benefit year. The platform automatically applies the correct thresholds for every county in your service area — you do not need to manually extract, format, or enter data from the HSD file.

When CMS publishes the updated file each October, Blueprint applies the new thresholds automatically. Plans using Blueprint enter each new benefit year with thresholds already updated — no manual refresh required.

Common HSD Reference File Mistakes

The most common errors related to the HSD Reference File that Blueprint sees in new client onboarding reviews:

• Using prior-year thresholds: Plans that don't update their models for the new benefit year file against outdated standards. CMS checks the submitted county classifications against the current HSD file during review.
• Incorrect county classification: Counties that reclassified from suburban to urban (or vice versa) change the applicable thresholds. A county that was suburban last year may now be urban, with tighter requirements.
• Misidentifying the HSD specialty for contracted providers: A provider who is contracted as a "general surgeon" may need to be mapped to a different HSD category depending on their primary board certification and the services they provide in-network.
• Missing the telehealth eligibility update: The list of telehealth-eligible specialties has changed in recent benefit years. Plans that don't update their models may count telehealth providers for specialties that no longer qualify — or miss credit for specialties that newly qualify.