Every quarter, MSSP ACOs must notify newly assigned beneficiaries of their rights under the Shared Savings Program, and keep proof of it for at least 10 years. Across 511 ACOs and 12.6 million beneficiaries, the Beneficiary Information Notice (BIN) is one of the program’s most routine requirements. It is also one of the easiest to get wrong, because the population changes every quarter and the documentation has to keep up.

When that process runs on spreadsheets, shared inboxes and manual mail tracking, the gaps show up fast: undelivered letters with no second attempt, follow-ups no one can prove happened, and no clean evidence to hand over when CMS asks.

CMS’s updated Beneficiary Notification and Education Guidance (Version 4, September 2026) clarifies what ACOs must do and how to document it. A pending rule change may also reshape the follow-up requirement. Here’s what you need to know, and how to build a process that’s audit-ready every quarter.

What the BIN Requires

Under 42 CFR 425.312, MSSP ACOs or their participants must give each qualifying Original Medicare beneficiary a standardized written notice. The BIN informs beneficiaries that their providers participate in the Shared Savings Program and explains their rights, including how their data may be used, their option to decline claims data sharing, their ability to choose a primary clinician through voluntary alignment, and their continued freedom to see any Medicare provider.

The BIN is a CMS template, not a letter ACOs write themselves. Per CMS’s 2026 guidance:

  • ACOs must use the most current template in the Marketing section of ACO-MS
  • Only CMS-designated fillable fields may be customized. ACOs may add their letterhead and logo.
  • Optional sections cover the SNF 3-Day Rule Waiver, telehealth and the Beneficiary Incentive Program. They’re included only if they apply, and the BIP section is required for ACOs operating a CMS-approved BIP.
  • ACOs may translate the BIN, but they’re responsible for its accuracy and must document which versions went to which beneficiaries. CMS provides Spanish templates.
  • ACO participants must display the CMS Poster in all facilities. It can be enlarged but never reduced or altered.
  • The BIN must be available on request wherever beneficiaries receive primary care

When the BIN Must Be Delivered

ACOs must furnish the BIN at least once per agreement period. Timing depends on assignment methodology:

Assignment Method When the BIN Is Due
Preliminary prospective with retrospective reconciliation Before or at the beneficiary’s first primary care visit, in the first performance year they receive primary care from an ACO participant during the agreement period
Prospective During the first performance year the beneficiary is prospectively assigned, in each agreement period

The 180-Day Follow-Up

After the BIN is delivered, the ACO or ACO participant must follow up with the beneficiary, verbally or in writing, within 180 days. The window is rolling: it runs from the date each individual beneficiary received the BIN, and it can extend into the next performance year. Acceptable follow-ups include an FAQ sheet, a care coordination mailing, a text or patient portal message inviting questions, or a phone call. ACOs must record the type and date of each beneficiary’s follow-up.

Because every beneficiary has their own clock, CMS advises tracking follow-up at the beneficiary level. That’s nearly impossible to manage reliably in spreadsheets.

A Proposed Change: Removing the 180-Day Follow-Up

CMS’s CY 2027 Physician Fee Schedule proposed rule included a proposal to remove the 180-day follow-up communication requirement. CMS is expected to address the proposal in the final rule, anticipated before November 1, 2026.

Until a final rule takes effect, the requirement stands. CMS’s September 2026 guidance still lists the follow-up as a compliance obligation, and a missed follow-up remains a reportable gap. Even if the requirement is removed going forward, ACOs will still need records for follow-ups already owed, as well as beneficiary-level proof of BIN delivery for the full 10-year retention window.

Where BIN Compliance Quietly Falls Apart

The Population Changes Every Quarter

The workflow runs on two data clocks. Per CMS’s CCLF Information Packet, Claim and Claim Line Feed (CCLF) files release monthly, while assignment reports (ALR and QALR) run quarterly. Each quarterly update determines which beneficiaries need a BIN. That means a new list, a new batch of addresses to verify, and a new set of individual follow-up clocks, every quarter, with no extra staff.

Records Are Scattered Across Channels and Practices

One practice hands out the BIN at the front desk, another emails it through the portal, and the ACO mails the rest. Each channel produces its own records, or none at all. CMS’s guidance recommends exactly the opposite:

“Establish and maintain a centralized tracking at the start of each agreement period that consolidates delivery records across all channels.”
 CMS Beneficiary Notification and Education Guidance, V4

Audit Trails Get Built After the Audit Notice Arrives

Many ACOs assemble documentation only when CMS asks. That works until the request comes with a short turnaround and the records are spread across years of email and file exports.

The stakes are real. CMS states that failure to provide the BIN, the follow-up communication or the Poster display can trigger a Corrective Action Plan under 42 CFR 425.216 or termination of the participation agreement under 42 CFR 425.218.

Manual vs. Centralized BIN Compliance

Manual (Spreadsheets + Shared Drives)

Centralized Workflow

CMS file processing

Staff parse files by hand each quarter

Automated ingestion of CCLF and assignment files

Address quality

Errors found after letters bounce

CASS-certified verification before mailing

Delivery tracking

Records split across channels and practices

All channels consolidated in one record

Follow-up

Individual 180-day clocks tracked by hand

Follow-up date and method logged per beneficiary

Audit response

Records reconstructed under deadline

Exportable record, ready on demand

Scale

Staff time grows with population

Scales without added headcount

How to Build an Audit-Ready BIN Process

  1. Verify addresses before you mail. Most rework in BIN compliance traces back to bad addresses and late detection. USPS CASS certification cuts undeliverable volume before it becomes a tracking problem.
  2. Use multiple channels, with consent. CMS recognizes in-person delivery, mail, on-site display and electronic delivery by email or patient portal. Electronic delivery requires the beneficiary’s prior consent and compliance with federal and state privacy laws. An email-first approach for consenting beneficiaries, with a tracked mail fallback for everyone else, reaches more people faster.
  3. Close the loop on undeliverable mail. When a notice comes back, check with the beneficiary’s PCP for an updated address, attempt phone contact, re-mail, and document each step.
  4. Keep the BIN standalone. CMS allows ACOs to send newsletters, care coordination updates and other materials alongside the BIN, but the BIN must remain a separate, unaltered document. Supplemental materials that describe the ACO’s Shared Savings Program participation may count as marketing under 42 CFR 425.310. Pre-clearance ended in 2023, but CMS can still request and disapprove materials at any time.
  5. Use one system of record. Consolidate delivery, follow-up and undeliverable records across every channel and practice, as CMS recommends, so compliance has one place to answer from.

Audit-Ready Checklist

For every beneficiary who needed a BIN, you should be able to produce:

  • ☐ The template version and language sent
  • ☐ Delivery date, channel and outcome
  • ☐ Consent on file for electronic delivery
  • ☐ Undeliverable status, address correction and re-send attempts
  • ☐ Follow-up date and method (while the requirement remains in effect)
  • ☐ Poster display at every participant facility
  • ☐ Records retained for 10 years under 42 CFR 425.314

If any of these takes more than a few minutes to pull, your process isn’t audit-ready yet.

How Mabel Manages BIN Compliance for MSSP ACOs

Mabel’s BIN compliance workflow gives MSSP ACOs the centralized tracking CMS recommends, without adding staff:

  • CMS file parsing: Ingests quarterly assignment and CCLF files and identifies who needs a notice
  • Multichannel delivery: Email for consenting beneficiaries, with CASS-verified mail fallback
  • Undeliverable tracking: USPS tracking feeds a compliance dashboard where staff can download returned-mail lists, add updated addresses and notes, and re-upload
  • Beneficiary-level records: Every send, delivery outcome and follow-up logged automatically and ready for audit
  • Built to adapt: As CMS finalizes changes to the follow-up requirement, your workflow updates without rebuilding your process
  • Security: Independently assessed annually under a SOC 2 Type II program

“Between parsing the CMS files, handling the letters that go out, and digitally tracking undeliverable mail, Mabel is critical to our ACO’s operations. Our lean team would not be able to stay compliant without Mabel.”
 Manager, Value-Based Contract Operations, MSSP ACO

See how Mabel would streamline your BIN process →

 

Make Audit Readiness a Standing Capability

The BIN requirement doesn’t pause between audits, and the population it covers changes every quarter. With CMS updating its guidance and a final rule pending on the follow-up requirement, ACOs need a process that’s accurate today and flexible enough to adapt. A centralized workflow keeps your compliance record complete as your population grows and the rules change.

Schedule a walkthrough with Mabel →

Frequently Asked Questions

How often does a beneficiary need to receive a BIN?

At least once per agreement period. Under preliminary prospective assignment, the BIN is due before or at the first primary care visit in the first performance year the beneficiary receives primary care from an ACO participant. Under prospective assignment, it’s due during the first performance year the beneficiary is prospectively assigned.

Is the 180-day follow-up still required?

Yes, for now. CMS’s CY 2027 Physician Fee Schedule proposed rule proposed removing it, and the final rule is expected before November 1, 2026. Until a change takes effect, ACOs must follow up within 180 days of each beneficiary’s BIN delivery and document the date and method.

Does the follow-up have to be in writing?

No. It can be verbal or written, such as a phone call, FAQ sheet, mailing, text or portal message. It should give the beneficiary a chance to ask questions about the ACO and their rights. That flexibility shifts the compliance burden onto recordkeeping: the record of when contact happened, and in what form, is the artifact an auditor reviews.

Can an ACO send the BIN by email?

Yes. CMS recognizes email and patient portal delivery, provided the beneficiary has given prior consent and the ACO complies with applicable privacy and electronic communication laws.

Can an ACO customize the BIN?

Only within limits. ACOs may use their letterhead and logo, fill in CMS-designated fields, include applicable optional sections and translate the notice. CMS-protected content cannot be changed.

How long must BIN records be kept?

Ten years from the end of the agreement period or the completion of any audit, whichever is later, under 42 CFR 425.314. This includes records of both the BIN and the follow-up.

Are materials sent with the BIN considered marketing?

Sometimes. General health education, preventive reminders and care coordination materials usually aren’t. Materials that describe the ACO’s Shared Savings Program participation, such as a “we joined an ACO” letter, are marketing under 42 CFR 425.20 and must meet the requirements of 425.310.

What’s the difference between a BIN and a BNL?

BIN is the MSSP Beneficiary Information Notice. BNL is the Beneficiary Notification Letter used in ACO REACH and the LEAD Model starting in 2027. Each has its own rules, so organizations in both programs need separate tracking. Mabel supports both BINs and BNLs.