ACO REACH ends December 31, 2026, and the Long-term Enhanced ACO Design (LEAD) Model launches January 1, 2027. An estimated 14.3 million Medicare beneficiaries are enrolled in an ACO of some kind in 2026, according to CMS’s own enrollment estimate, and a meaningful share of that population is about to move to a successor model.
Every REACH participant is running two clocks at once. One counts down to a final social determinants of health (SDoH, also known as Upstream Drivers of Health (DR), and formerly referred to as Health Equity Data Reporting or HEDR) submission for Performance Year 2026. The other counts up to LEAD’s first performance year. Planning the REACH-to-LEAD transition as a single continuum — rather than two separate projects — keeps outreach workflows unified, vendor contracts consolidated, and reporting formats consistent. Mabel supports REACH’s SDoH survey collection and reporting today, along with the voluntary alignment and beneficiary notification infrastructure LEAD will require starting in 2027.
Why ACO REACH Ends This December
The model is closing from a position of financial strength. In Performance Year 2024, REACH ACOs generated $988.3 million in net savings across roughly 2.5 million beneficiaries, with 96 of 115 participating ACOs earning shared savings and average quality scores climbing from 79.42% to 81.11% year over year. By Performance Year 2026, only 74 ACOs remain on CMS’s official PY2026 participant list, down from 132 in 2023, signaling consolidation ahead of the sunset.
Those 74 organizations are required to submit SDoH data reporting for PY26 aligned beneficiaries to CMS before the model closes. For any organization still building its SDoH collection process, the window is narrowing.
Closing Out REACH While Building for LEAD
Executing the transition while a performance year is still open is where careful consideration matters most.
Finishing What REACH Started
REACH ACOs must submit beneficiary-level SDoH data for all beneficiaries with at least 6 months of alignment as of October 1, 2026, using one of three CMS-approved instruments: the CMS Accountable Health Communities (AHC) screening tool, the North Carolina questionnaire, or the NACHC PRAPARE tool.
The DR Adjustment (formerly HEDR) can add up to 5 percentage points to an ACO’s Total Quality Score for PY26, per CMS’s quality and MSR methodology documentation, based on the completeness of SDoH reporting. This adjustment applies to a Quality Withhold that has increased from 2% to 5% of the Financial Benchmark for PY26, and it determines how much of that withhold the ACO recovers at financial settlement. SDoH collection is tied to money already earned but not yet received, so organizations need a clear, CMS-formatted record of who was surveyed, when, and how.
In the same 2026 rule cycle, CMS eliminated Quality ID 487, its mandatory Screening for Social Drivers of Health measure, from MSSP’s required quality set. REACH’s SDoH requirement and MSSP’s quality measure are separate programs and separate data, but the divergence signals that CMS’s appetite for mandatory SDoH reporting is not moving in one direction across its ACO models.
Building LEAD’s Alignment and Notification Engine
LEAD carries forward two operational functions from REACH: voluntary alignment and Beneficiary Notification Letters (BNLs). ACOs can identify eligible beneficiaries with a provider’s panel, execute outreach campaigns encouraging beneficiaries to join an ACO through voluntary alignment, keep an audit of the voluntary alignment forms received, send BNLs to newly aligned beneficiaries, and document delivery and follow-up on any undeliverable mail.
The implementation period between application acceptance and January 1, 2027 is the practical window for building this infrastructure. Waiting until Performance Year 1 means building it alongside new financial risk.
Two Compliance Clocks, One Calendar
The core challenge of this period is that REACH’s closeout obligations and LEAD’s startup obligations land at the same time. Compliance teams that build REACH’s SDoH data reporting process and beneficiary close-out notifications as a one-off effort now face standing up a similar beneficiary outreach process for LEAD (voluntary alignment and beneficiary notification letters) almost immediately afterward. Run as two separate efforts, that means two vendor relationships, and two audit trails to maintain in parallel.
A single outreach and reporting infrastructure removes that duplication. Personalized, provider-branded direct mail paired with digital response options like QR codes, along with email, is widely regarded as one of the highest-leverage channels for SDoH data collection, voluntary alignment campaigns, and beneficiary notifications.
Mabel in Practice
In an analysis of 100,000 Medicare lives across multiple TINs, Mabel found that only 40% of its beneficiaries were claims-aligned. One ACO REACH participant with 40% claims alignment running voluntary alignment claims in-house had as much as a 50% rejection rate due to MBI errors, NPI/TIN mismatches, and several other manual errors. After Mabel took over campaign execution, response processing, and CMS submission management, the organization saw a 30% increase in net-new alignments over 12 months and the preventable error rate dropped to <1%.
A second ACO REACH partner approached Mabel shortly before its Performance Year 2023 SDoH deadline after in-house outreach fell short. Using a coordinated campaign across email, direct mail, and EHR-embedded surveys, the organization captured more than 90% of its required SDoH data within two weeks, putting it on track to recover the full $100,000 adjustment tied to its quality withhold.
What REACHs Should Do Before LEAD Performance Year 1 Begins
Treat PY2026 SDoH collection — REACH’s final performance year — as a defined, time-boxed project: segment the beneficiary population that still needs a response, prioritize outreach by provider or practice, and keep every response logged in a CMS-submission-ready format. The requirements described in CMS’s PY2026 quality measurement methodology don’t change based on how much time remains.
Then use LEAD’s Implementation Period — beginning September 15, 2026 — to run a full dry cycle: a voluntary alignment campaign, a CMS submission, and beneficiary notifications via email and/or mail. That trial run surfaces gaps in segmentation criteria, provider data, or vendor handoffs while there’s still time to fix them.
If your team is weighing how to staff and structure LEAD’s alignment and beneficiary notification requirements, reach out to Mabel to talk through what that transition looks like for your organization.
Frequently Asked Questions
If a REACH ACO wants to join MSSP instead of LEAD, does it follow the same application timeline?
No. The Medicare Shared Savings Program runs its own annual application cycle with deadlines set well before each performance year begins, entirely separate from LEAD’s request for applications, according to CMS’s Shared Savings Program overview.
MSSP’s cycle typically opens in late spring, with the application window falling in May and June and new or renewing ACO agreements taking effect the following January 1. The PY2026 window, for example, ran May 29 through June 12, 2025.
That structure runs independently of LEAD, which used a single RFA window for its first cohort: CMS released the request for applications on March 31, 2026, with full applications due May 17, 2026, tied to the January 1, 2027 launch. CMS separately accepted non-binding letters of interest through April 20, 2026 from organizations considering future LEAD cohorts, a signal that later application rounds may follow.
For a REACH ACO evaluating its options as the model winds down, this means MSSP is not a fallback sharing LEAD’s clock. An organization considering that path needs to track MSSP’s current-year application deadlines directly with CMS. Whichever destination an ACO chooses, the voluntary alignment and beneficiary notification work carries over; Mabel’s platform supports both MSSP and LEAD workflows, so the infrastructure decision doesn’t have to wait on the program decision.
Has CMS published the specific Beneficiary Notification Letter rules ACOs will follow under LEAD?
Not yet in full. CMS’s Innovation Insight on the LEAD Model and its request for applications describe program structure and participation requirements but stop short of the REACH-level operational detail on BNL timing and content that already exists in REACH’s program manuals and newsletters.
Under REACH, that detail includes specific guidance on sending BNLs to newly aligned beneficiaries, documenting delivery, and following up on undeliverable mail, all built up over multiple program years of newsletters and manual updates.
Does LEAD require whole-TIN participation, or can ACOs enroll providers selectively the way they could under REACH?
LEAD requires whole-TIN participation, meaning an entire practice group’s Tax Identification Number must join together rather than enrolling individual providers by National Provider Identifier, according to Benesch Law’s comparison of LEAD and ACO REACH.
That is a meaningful change from REACH, which allowed ACOs to select individual providers rather than committing an entire practice at once.
Under REACH’s NPI-level flexibility, an ACO could build a network around its highest-performing providers while leaving others out. LEAD’s whole-TIN structure removes that option, so a practice group’s full roster, including providers with less consistent performance, joins together as a unit.That being said, the TIN-model instead of NPI-model helps simplify voluntary alignment best practices and is an improvement in LEAD compared to REACH.
Does the LEAD Model include an SDoH or health equity data reporting requirement similar to ACO REACH?
Not according to CMS’s currently published materials. Neither CMS’s LEAD Model FAQ nor its Innovation Insight page describes a health equity or SDoH data reporting obligation comparable to REACH’s UDR framework, though CMS could still add operational detail before Performance Year 1 begins.
That is a notable contrast with REACH, where SDoH performance is tied directly to a defined share of an ACO’s quality withhold and financial settlement.
If CMS eventually introduces a similar requirement for LEAD, REACH’s existing framework, built around CMS-approved screening instruments and beneficiary-level submission specifications, is the most likely template it would follow.
Exactly how much smaller can a high-needs ACO be under LEAD’s beneficiary threshold?
ACOs whose aligned population includes more than 40% High Needs beneficiaries can qualify with as few as 800 aligned beneficiaries in Performance Year 1, with at least 500 claims-based beneficiaries aligned in a Base Year, well below LEAD’s standard 5,000-beneficiary minimum, according to CMS’s own LEAD Model FAQ.
This lower threshold reflects a broader design choice in LEAD: rather than segregating high-needs beneficiaries into a separate track the way REACH did with its High Needs Population ACOs, LEAD folds those beneficiaries into the standard model with an adjusted entry point.
How do beneficiary incentives compare between LEAD and ACO REACH?
LEAD expands what ACOs can offer beneficiaries well beyond REACH’s incentives, permitting Part B copay waivers, in-kind benefits, and potentially subsidized Part D premiums by 2029 under expanded fraud and abuse waivers, according to Benesch Law’s comparison of the two models.
REACH’s incentive structure, by contrast, was largely limited to smaller rewards like gift cards for completing primary care visits.
LEAD’s broader set of allowable incentives gives ACOs more direct tools to reduce cost barriers to care and encourage beneficiaries to stay engaged with their aligned provider over the model’s 10-year term.
For Medicare growth and patient engagement teams, this is a meaningfully different toolkit to plan around, not simply a bigger version of REACH’s incentives. Decisions about which incentives to offer, and how to communicate them to beneficiaries, will need to account for expanded waiver protections that did not exist in the same form under REACH.
