How CMS actually measures time and distance.
Most people have a general sense of time-and-distance standards. The specifics are where plans get surprised: who runs the calculation, which county type you're in, and how the percentage test works.
Time and distance is the most commonly misunderstood component of Medicare Advantage network adequacy. Plans have a general sense that CMS measures how far members have to travel to see a provider, and that there are different standards for urban versus rural counties. The specific mechanics are where surprises happen: how CMS runs the calculation, which county type each county falls into, what the percentage threshold is, and where state rules do and don't apply.
CMS runs the calculation, not you
For each specialty and county type, CMS sets a maximum travel time in minutes and a maximum distance in miles. The time limit is where geography shows up. In markets with geographic barriers (major interstates, rivers, mountainous terrain), a provider who is five miles away as the crow flies might be a 45-minute drive. Plans that model coverage with straight-line radius circles tend to overstate it.
CMS measures travel time and distance from beneficiary locations drawn from its MA Medicare Sample Census to the providers on your HSD tables, and it runs that calculation itself in the HPMS Network Management Module. You don't submit your own numbers. If you model adequacy before submission, and you should, model it the way CMS does: from where beneficiaries actually live in each county, not from county centroids.
The five county types
CMS applies different standards based on county type. It sorts every county into one of five types based on population size and density: Large Metro, Metro, Micro, Rural, and Counties with Extreme Access Considerations (CEAC). The maximums for primary care and cardiology show how far the standard moves from one type to the next:
- Large Metro: primary care 10 minutes / 5 miles; cardiology 20 minutes / 10 miles.
- Metro: primary care 15 minutes / 10 miles; cardiology 30 minutes / 20 miles.
- Micro: primary care 30 minutes / 20 miles; cardiology 50 minutes / 35 miles.
- Rural: primary care 40 minutes / 30 miles; cardiology 75 minutes / 60 miles.
- CEAC: primary care 70 minutes / 60 miles; cardiology 95 minutes / 85 miles.
Every other specialty and facility type has its own pair of values in the same table. These thresholds are applied at the county level using the census-based distribution of beneficiaries in each county, not the provider's location. A provider in a Metro county who serves beneficiaries in a neighboring Rural county is measured against the Rural standard for those beneficiaries.
Specialty-specific thresholds
CMS's specialty-specific time and distance standards are codified at 42 CFR 422.116 and published each year in the HSD Reference File. Each specialty and facility type has its own values. A few categories are worth calling out:
- Behavioral health: CMS has been adding specialty types here. Clinical psychology and clinical social work came in with the CY2024 rule, and Outpatient Behavioral Health with the CY2025 rule. If you contract with telehealth providers in certain specialties, including psychiatry, clinical psychology, clinical social work and outpatient behavioral health, CMS lowers the share of beneficiaries who must be within time and distance by 10 percentage points. It is a credit, not a substitute for in-person access.
- Hospital services: Acute inpatient hospitals are evaluated separately from physician access. They have their own time-and-distance values plus a minimum-bed standard measured per 1,000 beneficiaries.
The percentage threshold problem
CMS does not require 100% of members to be within the time-distance standard for every specialty. It requires a certain percentage of beneficiaries in each county to have access. The threshold is 90% of beneficiaries in Large Metro and Metro counties and 85% in Micro, Rural and CEAC counties, and it is the same for every specialty, including primary care.
This means you can pass the adequacy review with some members outside the standard, but the percentage calculation is applied county by county, not at the market level. A county that fails is a county that fails, regardless of how well your other counties perform. Plans that model adequacy at the market level and discover county-level failures at submission have a difficult problem to solve on a short timeline.
Where state rules fit
For Medicare Advantage, CMS standards govern network adequacy and override state rules. The state still licenses the plan, and its own standards apply to your Medicaid and commercial products. If one network serves several product lines, the same providers can be measured against the CMS tables for MA and against the state's standards for everything else.
For Medicare Advantage, the CMS standard is the one that counts. State standards matter for the Medicaid and commercial products that share your network.
If the same network serves Medicaid or commercial members, pull the state's standards alongside the CMS tables and model each product against its own rules. The two sets of standards don't always match, and a network that passes one can still fall short on the other.
Sources: 42 CFR 422.116 (time and distance, county types, percentage thresholds, telehealth credit); CMS network adequacy guidance, December 2024; 42 CFR 422.402 (federal preemption of state law).