Value-based care solutions live or die on one number: how many beneficiaries an ACO can prove are aligned to it. For ACOs accepted into CMS’s Long-term Enhanced ACO Design (LEAD) model, that number now has a date attached to it.

LEAD’s implementation period runs September 15 through December 31, 2026, and CMS describes it as the window for participating ACOs to conduct voluntary alignment activities before the beneficiary alignment minimum applies. Performance Year 1 opens January 1, 2027. Standard ACOs need 5,000 aligned beneficiaries by then.

That turns a strategy conversation into an operations problem with roughly a hundred days on the clock. Mabel builds voluntary alignment infrastructure for ACO REACH participants and other value-based care organizations working through exactly this problem, at the volumes LEAD will require.

Not Every Beneficiary Counts: What LEAD Means by “Aligned”

Aligned lives are not simply patients an ACO treats. A beneficiary counts toward LEAD’s thresholds only if the alignment was generated the way CMS specifies, and LEAD recognizes two paths.

Claims-based alignment happens automatically, with CMS matching beneficiaries to an ACO using their claims history, per the LEAD alignment and finance paper. Voluntary alignment happens when a beneficiary actively selects an ACO-affiliated provider as their primary source of care, independent of claims.

The tiered thresholds set different starting lines for different organizations, per CMS’s LEAD Request for Applications webinar slides:

ACO Type Performance Year 1 Minimum Base Year Minimum
Standard ACO 5,000 aligned beneficiaries 3,000 aligned
High Needs Focused ACO (40%+ high-need population) 800 aligned beneficiaries 500 claims-based aligned
Newly Entering ACO 1,000 aligned beneficiaries 600 claims-based aligned

None of these totals move on their own. An ACO has to generate its voluntary share through outreach it runs, tracks, and documents itself. High Needs Focused ACOs face a harder targeting problem underneath that lower threshold, since many of those beneficiaries are homebound, in long-term care, or reachable only through a caregiver or proxy.

Meeting the minimum also determines which of two payment structures an ACO can use. Professional Risk caps both savings and losses at 50% with no benchmark discount. Global Risk raises that ceiling to 100% on both sides, applies a 1.75 to 3% discount, and adds access to Total Care Capitation, per CMS’s LEAD payment fact sheet.

Two Paths to the Threshold: How Alignment Growth Works

ACOs choose between two alignment structures. Prospective alignment fixes the beneficiary population for the full performance year. Hybrid alignment allows monthly voluntary additions plus one mid-year opportunity to add new participant TINs.

Either way, voluntary alignment requires the same underlying work: identifying eligible beneficiaries, reaching them, processing responses, and submitting results to CMS in the format it expects.

Per CMS’s comparison of LEAD, ACO REACH, and MSSP, MSSP runs on renewable five-year agreements with no end date and a more restrictive risk structure, while ACO REACH, winding down after Performance Year 2026, shares LEAD’s risk options but lacks its capitation tools.

Where Alignment Campaigns Break Down

Voluntary alignment has a rocky track record. A study in the American Journal of Managed Care found that in the Next Generation ACO Model, LEAD and REACH’s predecessor, only 29% of participating ACOs ever got as much as 1% of their population voluntarily aligned, and just two organizations exceeded 10%.

CMS’s own evaluation of ACO REACH found a similar spread. New Entrant ACOs voluntarily aligned 58% of their population, against 8% for Standard ACOs and 10% for High Needs ACOs, per the third ACO REACH evaluation report. That gap reads as an implementation story more than a policy one. ACOs treating voluntary alignment as a dedicated operational build are the outliers, not the norm.

Running direct mail, email, and in-clinic outreach as separate, uncoordinated efforts creates duplicate contacts and manual data entry that produces errors: a missing or mismatched Medicare Beneficiary Identifier, a provider NPI not on file, a signature date discrepancy. Left unresolved, those forms represent beneficiaries the campaign successfully reached but still cannot count toward the minimum.

Coordinating channels around a single beneficiary record, with every form routed through the same validation step, is the direct fix. It also matters at audit, since CMS asks not only whether an ACO grew its aligned lives but whether every beneficiary counted got there through a documented, timestamped process.

Mabel in Practice: From Rejected Forms to 30% More Net-New Alignments

Across more than 100,000 fee-for-service lives spanning several ACO REACH organizations, Mabel found that only about 40% of eligible beneficiaries were claims-aligned, and that rejection rates from simple data-entry errors ran as high as 50% on submitted forms.

That was the starting point for one large ACO REACH participant that brought Mabel in to rebuild its voluntary alignment process across three stages: campaign execution over direct mail, email, and in-clinic touchpoints; response processing with a quality-control step; and alignment tracking through to CMS submission. Over 12 months, the ACO recorded a 30% increase in net-new alignments, per Mabel’s published case study.

The ACO’s own account of the before state: “We previously handled voluntary alignment and beneficiary notification letters in-house, but it required a large team, was a huge headache, and resulted in a number of errors.”

That figure comes from ACO REACH, not LEAD, since LEAD has not yet completed a performance year. The relevance is structural: LEAD’s alignment mechanism mirrors REACH’s and the same bottlenecks appear at similar volumes. For scale, the full PY2023 REACH cohort of 132 ACOs generated $1.643 billion in gross savings, with 73% achieving net savings for CMS, per CMS’s PY2023 financial and quality performance results.

The Implementation Period Is the Whole Runway

LEAD’s first-cohort application window closed May 17, 2026. For the ACOs that got in, the open question is no longer whether they qualify but whether they clear the alignment minimum before Performance Year 1 opens on January 1, 2027.

That is a logistics problem before it is a strategy problem, and the runway is shorter than the industry asked for. NAACOS CEO Emily Brower has publicly argued that LEAD’s January 2027 start does not give current REACH participants “enough time to evaluate alternative payment model options and effectively plan their transition,” per Fierce Healthcare’s coverage of the LEAD announcement.

The minimum itself is not moving. If your ACO is sizing up what it will take to hit LEAD’s alignment minimum inside the implementation period, Mabel’s voluntary alignment infrastructure is built for this kind of timeline. Get in touch to see what that looks like against your current aligned-life count and your Performance Year 1 target.

Frequently Asked Questions

Does LEAD include any incentives for beneficiaries themselves, not just ACOs?

LEAD includes incentives aimed directly at beneficiaries, not only at the ACOs enrolling them. Per CMS’s LEAD model materials, those incentives include Part B cost-sharing support and a planned Part D premium buy-down arriving by 2029. The buy-down lets qualifying ACOs partially or fully offset a beneficiary’s Part D premium, separate from ACO-level payment structures like capitation, which gives an ACO’s outreach a selling point beyond continuity of care.

Do LEAD’s aligned-beneficiary minimums increase in later years?

LEAD’s aligned-beneficiary minimums increase in later years for two of the three ACO tiers. Standard ACOs stay flat at 5,000 for the full 10-year run, while Newly Entering ACOs move from 1,000 in Performance Year 1 to 5,000 by Performance Year 5, and High Needs Focused ACOs move from 800 to 1,600 over the same stretch before holding flat through Performance Year 10.

The 5,000-beneficiary standard threshold is a starting point for two of the three tiers, not a permanent target once cleared.

What’s the difference between LEAD’s hybrid alignment and ACO REACH’s Prospective Plus alignment?

The difference is cadence. LEAD’s Hybrid alignment adds voluntarily aligned beneficiaries monthly, while ACO REACH’s Prospective Plus adds them quarterly, per CMS’s model comparison. Both let an ACO add beneficiaries during the performance year instead of locking the population in upfront. For a team used to REACH’s quarterly rhythm, that means response processing and CMS submission shift to a monthly cycle under LEAD.

What happens if an ACO doesn’t reach its aligned-life minimum by Performance Year 1?

CMS has not published a standard penalty structure for this scenario in current LEAD materials, so ACOs should confirm the consequences through their model agreement.

The closest documented precedent sits in MSSP: under 42 CFR 425.110, an ACO whose assigned population falls below its minimum enters a corrective action period, and if the shortfall is unresolved CMS terminates the agreement and the ACO forfeits shared-savings eligibility. That is an MSSP rule rather than a confirmed LEAD one, but a reasonable signal of what falling short tends to trigger.

Will there be another chance to apply to LEAD after the first cohort?

CMS has noted future opportunities to apply beyond the initial cohort without publishing details of the next window as of this writing. Organizations planning around a later cohort should watch CMS’s LEAD model page directly before committing to a beneficiary-growth timeline.

They should also expect the same documentation depth the first round required, including a financial guarantee mechanism such as an escrow account, surety bond, or letter of credit, which is not something an ACO assembles in the final weeks before a deadline.