The CMS Annual Call Letter and What It Means for Network Adequacy

What the Annual Call Letter Is — and When It Arrives

Every year, CMS publishes the Medicare Advantage and Part D Annual Call Letter (formally, the "Advance Notice and Call Letter") in two stages. The Advance Notice typically arrives in late February, laying out proposed rate changes and policy updates. The final Call Letter follows in late March or early April, confirming the binding policy direction for the upcoming contract year. For network adequacy purposes, the final Call Letter is what matters — it contains the authoritative Health Service Delivery (HSD) table updates, time-and-distance standards, and any changes to required provider type categories.

Network ops teams that wait for the final Call Letter before beginning gap analysis are already behind. Experienced teams begin modeling against the Advance Notice in February so they can move into active recruitment as soon as the final standards are confirmed. The window between Call Letter publication and the HPMS network adequacy filing deadline is measured in weeks, not months — and any newly required specialty or tightened time-and-distance threshold that surfaces in the final Letter needs to be addressed in that window.

How the Call Letter Relates to Network Adequacy Standards

The Call Letter is the mechanism CMS uses to update its network adequacy standards on an annual basis. Each year's Letter confirms the final HSD table — the list of provider type categories that MA plans must satisfy for each county — and the time-and-distance (T&D) standards that apply to each category by urbanicity (urban, suburban, rural, and micro-rural). Changes to the HSD table can include: adding entirely new provider type categories (CMS has added telehealth mental health providers, mobile crisis teams, and medication-assisted treatment providers in recent years); retiring or consolidating existing categories; or adjusting the minimum number of providers required per 1,000 enrollees.

The T&D standards themselves — the maximum driving time and driving distance a member should face to reach an in-network provider — are confirmed in the Call Letter appendices. CMS has consistently tightened behavioral health T&D standards since 2020, reducing maximum drive times for mental health and substance use disorder providers in urban and suburban counties. Plans that do not track these year-over-year tightening trends risk discovering mid-filing that previously compliant counties are now deficient.

Key Sections Network Ops Teams Should Focus On

The Call Letter is a long document — typically 150 to 200 pages — covering rate methodology, star ratings, benefit flexibilities, and dozens of other MA program dimensions. Network ops teams should focus on a specific subset of sections. The network adequacy section (usually labeled "Network Adequacy" or cross-referenced under "Access to Care") contains the HSD table updates and T&D standard changes. The access standards section details any changes to the meaningful access or culturally and linguistically appropriate services requirements that interact with adequacy. The exceptions process section confirms whether CMS has updated the grounds for filing access exceptions and what documentation it will require.

A useful practice is to create a side-by-side comparison: take the prior year's Call Letter adequacy appendices and the current year's, and diff them line by line. Changes to the HSD table are often presented as redlines in the Advance Notice, making comparison easier. Any row where the minimum provider count, T&D threshold, or urbanicity classification has changed represents a direct operational action item. If a provider type is added to the HSD table for the first time, that is a recruitment requirement that may require months of lead time.

Tracking Changes from Prior Year

CMS publishes the prior year's final HSD table and T&D appendices alongside the current year's Advance Notice, which makes year-over-year comparison straightforward for teams that maintain their adequacy model in a structured format. The critical changes to track are: new provider type rows (net-new recruitment requirements); changes in minimum provider counts per 1,000 enrollees (can turn a compliant county deficient without any provider attrition); changes in T&D maximums (particularly common in behavioral health and primary care for rural categories); and changes in how CMS applies urbanicity classifications (RUCA code updates affect which T&D standard applies to a given county).

Teams that maintain a county-level adequacy model in a CRM or adequacy platform can re-run gap analysis against updated standards as soon as the final appendices are published. Teams that track adequacy in spreadsheets face a more manual process — and are more likely to miss a subtle change buried in the appendix tables. For multi-state plans, the volume of changes across all operating counties can be substantial even in years where the headline changes appear modest.

What to Do After Reading the Call Letter

The operational response to the Call Letter follows a predictable sequence. First, update the adequacy model with the new HSD table and T&D standards. Second, re-run gap analysis across all operating counties using the updated standards. Third, produce a gap report that identifies: counties newly deficient under the updated standards (previously compliant counties that fail under tightened thresholds); counties with newly required specialties (provider types added to the HSD table); and counties where T&D tightening creates access exceptions that will need to be filed. Fourth, prioritize recruitment resources against the gap report, with urgency assigned based on time to filing deadline and geography of the gap.

Network development leads should also use the Call Letter as an opportunity to brief plan leadership on any material changes to adequacy requirements. A Call Letter that adds a new specialty category or significantly tightens behavioral health T&D standards has direct budget implications — new recruitment, contracting, and potentially credentialing resources may be required. Leadership should understand the scope of the change before the HPMS filing window opens, not after.

The HPMS Schedule and the Filing Window

CMS publishes the HPMS network adequacy filing schedule as part of the annual Call Letter or in a separate HPMS memorandum released around the same time. The filing window for the upcoming contract year typically opens in late spring (May or June) and closes in summer (July or August), with the specific dates varying by year. Plans must submit their network adequacy data — provider counts by HSD category and county, gap documentation, exception requests — within the HPMS filing window. Late submissions are not accepted, and CMS can disapprove a contract application for failure to demonstrate adequate networks.

The gap between Call Letter publication and HPMS filing window opening is the operational runway network ops teams have to address gaps identified from the updated standards. This runway is typically 8 to 12 weeks. For straightforward contracting gaps in counties with available providers, this is sufficient time. For specialty gaps in rural or micro-rural counties, or for newly required provider types that require outreach to providers unfamiliar with MA contracting, this window is very tight. Plans that begin outreach in February against projected Call Letter changes are in a fundamentally better position than plans that wait for the final Letter before beginning recruitment.

Historical Patterns: Behavioral Health and Provider Type Expansion

Looking across Call Letters from 2019 through 2025, two consistent patterns emerge. First, CMS has tightened behavioral health time-and-distance standards in nearly every cycle, reducing maximum allowable drive times for mental health and substance use disorder providers in urban and suburban counties and adding new provider type sub-categories (outpatient SUD treatment, medication-assisted treatment, and mobile crisis services have all been added to the HSD table in this period). Plans that have historically treated behavioral health as a secondary adequacy concern — filing exceptions and moving on — have faced increasing compliance pressure as CMS has made behavioral health network requirements progressively more stringent.

Second, CMS has consistently expanded the HSD table's provider type list over time, adding categories that reflect new care delivery models (telehealth, home-based primary care, crisis stabilization) and population health priorities (maternal health, behavioral health integration). Each expansion represents a new recruitment requirement. Plans that maintain an ongoing awareness of CMS's stated policy priorities — which are telegraphed in the Request for Information process, CMS Innovation Center initiatives, and Congressional priorities well before they appear in the Call Letter — can begin positioning their networks for future requirements before they become binding obligations.