How CMS Calculates Time-Distance Standards: What Every Network Team Needs to Know

The Foundation: What Time-Distance Standards Actually Measure

Time-distance standards in CMS network adequacy are a proxy measure for member access. The underlying question is simple: can a plan member who needs a given type of care reach a contracted, available provider within a reasonable time and distance? CMS has translated that qualitative goal into quantitative thresholds — maximum travel time and maximum travel distance — that define what "reasonable" means for each specialty category in each county type.

Understanding how these thresholds are calculated matters for network teams because the calculation methodology has specific definitional choices that are not always intuitive. What counts as a "nearest" provider, what "available" means in the context of a panel-status determination, and how member population is represented in the calculation are all defined by CMS in ways that can produce different results than a network team might expect from a naive interpretation of the standard.

This guide works through the calculation methodology systematically — from the classification system that determines which threshold applies, through the specific definitions of "nearest" and "available," to the technical methods CMS uses for member population centroids and drive-time calculations. Understanding these details allows network teams to run internal adequacy calculations that align with CMS's HPMS outputs, rather than discovering discrepancies at the point of submission.

Point-to-Point vs. Drive-Time Distance

CMS measures time-distance using two methodologies simultaneously: straight-line (point-to-point) distance and drive-time distance. Both measures must satisfy the applicable threshold for a county-specialty combination to pass adequacy. If either measure fails, the combination fails — even if the other measure passes.

Point-to-point distance is the straight-line geographic distance between the member population centroid and the provider practice location, measured in miles. This is the simpler of the two measures and is calculated using standard geodesic distance formulas applied to the latitude-longitude coordinates of both points. CMS uses the WGS84 coordinate system for these calculations, which is the standard used by GPS and most mapping services.

Drive-time distance is the estimated travel time by road between the same two points, measured in minutes. This calculation is significantly more complex than point-to-point distance because it requires a road network database and a routing algorithm. CMS uses a road network dataset and routing methodology specified in its technical documentation for HPMS; the exact dataset is not publicly disclosed but is consistent with commercial routing services used for logistics and mapping. Plans that run internal drive-time calculations using different road network data or different routing algorithms may produce results that differ from CMS's HPMS outputs.

The practical implication of dual-measure testing is that a provider who is close in straight-line distance may still fail the drive-time test if the road network between the population centroid and the provider location requires a circuitous route — as is common in areas separated by rivers, mountain ranges, or limited-access highway corridors. Network teams building in rural or geographically complex markets should verify both measures for marginal counties rather than assuming that a provider who passes the mileage test will also pass the drive-time test.

How CMS Defines "Nearest Available"

The adequacy standard is measured against the nearest available in-network provider in each specialty category — not against the distribution of all in-network providers. This means that for a given county-specialty combination, only the single closest available provider's distance from the population centroid determines whether the county passes or fails. A county with five cardiologists, four of whom are 80 miles away and one of whom is 15 miles away, passes the adequacy test based on the single nearest provider — assuming the applicable threshold is greater than 15 miles.

The word "available" carries specific definitional weight. For adequacy calculation purposes, a provider is "available" if they meet three conditions: they have an active, executed participating provider agreement with the plan; they have completed credentialing and their credentialing status is current and active; and they are accepting new patients (i.e., their panel is open). A provider who fails any one of these three conditions is excluded from the adequacy calculation, even if they are otherwise the nearest contracted provider in the specialty.

Panel status is the most operationally dynamic of these three conditions. Providers open and close their panels based on patient volume, staffing, and practice economics. A provider who passes the availability test in January may have a closed panel by June. This is why panel-status attestation cadence matters: if your adequacy calculation is based on panel-status data that is six months old, you may be counting providers who are no longer available in the regulatory sense.

CMS also applies a minimum availability threshold at the county level. For most specialty categories, a county must have at least a minimum number of available providers — typically stated as a percentage of the enrollee population who can access a provider within the applicable threshold — to pass adequacy. The percentage threshold varies by specialty category, county type, and the specific adequacy standard year. For 2025 benefit year submissions, CMS requires that at least 90% of plan enrollees in a county can access a provider within the applicable time-distance threshold for each specialty category.

Panel Status and Availability for Calculation Purposes

Panel status determination for adequacy purposes is more nuanced than the simple open/closed binary that most provider databases record. CMS's framework recognizes that panel status can be product-specific and member-population-specific — a provider may be accepting new patients for commercial insurance but not for Medicare Advantage, or may be accepting new adult patients but not new pediatric patients.

For Medicare Advantage adequacy, the relevant panel status is the provider's willingness to accept new Medicare Advantage plan members specifically. A provider who accepts Medicare fee-for-service patients but has opted out of all MA plan contracting is not "available" for MA adequacy purposes even if they are physically close to the member population centroid. Conversely, a provider who is contracted with your MA plan and accepting new MA plan members is available — even if their panel for other insurance products is closed.

This product-specificity creates a data management challenge. Most provider attestation forms ask about panel status in general terms — "Are you currently accepting new patients?" — without capturing product-level availability. Plans that collect product-specific panel status data are better positioned to accurately assess availability for adequacy purposes and to defend their panel-status determinations in an audit. Plans that rely on general panel-status attestations are operating with data that is inherently less precise than what CMS's availability definition contemplates.

A practical recommendation: when redesigning your provider attestation workflow, add a product-specific question — "Are you currently accepting new Medicare Advantage plan members?" — in addition to or instead of the general accepting-new-patients question. The responses will be more operationally relevant to your adequacy calculation and more defensible in a CMS data review.

RUCA Code Classification: The Driver of Which Standard Applies

Rural-Urban Commuting Area codes are the classification system CMS uses to determine which time-distance threshold applies to each county. The RUCA framework classifies geographic areas based on population density and the degree to which the local workforce commutes to urban areas — a proxy for the integration of a given area into an urban economy and, by extension, its access to urban-area healthcare providers.

CMS translates RUCA codes into four adequacy categories: urban, suburban, rural, and frontier/highly rural. The specific RUCA code ranges that map to each adequacy category are documented in CMS's annual network adequacy supplemental guidance and have been subject to periodic revision as CMS updates its methodology. The most consequential recent revision was CMS's incorporation of updated census data that reclassified dozens of counties nationally, shifting some from suburban to urban (triggering tighter standards) and some from rural to suburban (also triggering tighter standards relative to prior years).

The county-level RUCA classification is applied uniformly within each county for adequacy purposes, even though RUCA codes are technically assigned at the census-tract level. For adequacy calculations, CMS assigns each county the RUCA-based classification that reflects its dominant character — a county that is predominantly rural but has one urban census tract is classified based on the overall county profile, not the urban outlier tract. Network teams should verify county-level classifications directly from CMS's published classification table rather than inferring them from census-tract-level RUCA data.

Frontier and highly rural counties receive special treatment in the adequacy framework. For counties classified as frontier — typically defined as those with fewer than six persons per square mile — CMS recognizes that time-distance thresholds are often practically unachievable due to the genuine scarcity of healthcare providers. For these counties, the exception-filing pathway is broader, and CMS expects exception filings to be accompanied by documentation of the county's population density and the geographic constraints on provider availability, rather than just outreach logs demonstrating recruitment efforts.

How Member Population Centroids Are Used

The member population centroid is the geographic point from which CMS measures time-distance to the nearest available provider. For adequacy calculation purposes, CMS uses a weighted centroid that reflects the actual distribution of plan enrollees within the county — not the geometric center of the county polygon. This distinction matters in counties where the population is concentrated near one edge of the county (often near a county seat or urban center) rather than at the geographic midpoint.

CMS calculates the county-level population centroid from census block-level population data, weighted by the number of plan enrollees assigned to each block. In practice, this means that the centroid for a given county may shift from one benefit year to the next as the plan's enrollment distribution within the county changes. Plans with growing enrollment in a geographically distinct part of a county may see the centroid shift in ways that change the drive-time calculation to the nearest available provider — potentially changing a passing county to failing even with no change in the provider network.

Network teams should request the centroid coordinates CMS is using for each of their service area counties as part of their pre-submission validation process. CMS provides centroid data to plans through HPMS. Comparing the CMS-provided centroids against your internal calculation tool's assumptions is a straightforward spot-check that catches a common source of discrepancy between internal adequacy models and HPMS outputs.

Ghost Providers: Closed Panels and Their Impact on Availability

Ghost providers — a colloquial term for providers who appear in adequacy calculations as available but are not genuinely accessible to new patients — are one of the most significant accuracy problems in network adequacy submissions. Ghost providers take several forms: providers with formally open panels but appointment wait times so long that access is functionally unavailable; providers whose NPPES record is active but whose practice has wound down or relocated; providers who are contracted with the plan but have stopped accepting Medicare Advantage patients specifically; and providers who have retired or left the market but whose records haven't been formally deactivated.

CMS has taken an increasingly aggressive stance on ghost providers in adequacy audits. Secret shopper programs — where CMS contractors call provider offices posing as new patients seeking appointments — have identified ghost providers in submitted networks with enough frequency that CMS now treats provider directory accuracy and actual provider availability as separate adequacy compliance questions. A plan can pass the mathematical adequacy threshold while still failing a provider availability audit if the providers counted in the calculation are not genuinely accessible to members.

The practical response to the ghost provider problem is regular call-out testing — contacting a sample of providers counted in your adequacy calculation to verify appointment availability. Call-out testing should be weighted toward providers in specialty categories and counties that are at or near adequacy threshold, and the results should be documented with date, time, caller identity, and provider response. Plans that conduct call-out testing proactively, document the results, and remove ghost providers from their adequacy model before submission demonstrate the kind of diligence that satisfies CMS auditor expectations.

The Impact of Telehealth on Time-Distance Standards

Telehealth's role in network adequacy has been one of the most actively debated policy questions in MA plan compliance since the COVID-19 pandemic accelerated virtual care adoption. CMS has taken a position that is more nuanced than either "telehealth counts fully" or "telehealth doesn't count at all" — and the details of that position have significant operational implications for network teams.

As of the 2025 benefit year, CMS permits telehealth providers to count toward adequacy in a defined set of specialty categories and under specific conditions. Behavioral health — psychiatry, licensed clinical social work, and psychology — is the primary category where CMS has explicitly codified telehealth as an acceptable modality for adequacy purposes. For these specialties, a telehealth-only provider who is contracted with the plan and available to serve plan members can count toward the behavioral health adequacy calculation, subject to the condition that the plan offers members a viable telehealth access pathway (technology access, device accessibility support, member education).

For other specialty categories, telehealth providers may not be counted toward the time-distance adequacy calculation. The rationale is that time-distance standards were designed to measure physical access — the ability to reach a provider for in-person care — and telehealth providers, by definition, have no physical location relevant to the time-distance measurement. Plans that previously counted virtual-only providers toward adequacy in physical-access specialty categories should audit their adequacy models to ensure they are no longer doing so, as this practice has been a source of audit findings in recent program oversight cycles.

Blueprint automates the telehealth eligibility determination in its adequacy calculation engine — when a provider is flagged as telehealth-only in the network database, the system automatically restricts that provider to the specialty categories where telehealth credit is permitted and excludes them from time-distance calculations in physical-access categories. This prevents the inadvertent inclusion of virtual-only providers in physical-access adequacy counts that has generated findings for plans relying on manual calculation processes.