CMS’s August 26, 2026 Medicare Part D Claims Data 340B Repository FAQs establish an important new operational deadline for 340B covered entities. The repository will open for submissions on October 1, 2026.

Participation is voluntary for covered entities during 2026. However, CMS has proposed requiring Medicare providers and suppliers that are 340B covered entities to submit data beginning with claims dated January 1, 2027, as a condition of continued Medicare enrollment.

For FQHC CEOs, CFOs, 340B directors, pharmacy leaders, and compliance teams, this is not simply another CMS portal. It is a new claim-level data process that may require coordination across your in-house pharmacy, contract pharmacies, TPAs, billing teams, and executive leadership.

Important disclaimer: The potential 2027 reporting requirement is proposed, not final. This article is for informational and operational planning purposes only. It is not legal, regulatory, accounting, or compliance advice. Review current CMS guidance and obtain advice appropriate to your entity’s circumstances.

What Is the Medicare Part D 340B Repository?

The repository is connected to the Medicare Part D Inflation Rebate Program.

Under that program, manufacturers must pay CMS a rebate when the price of a rebatable drug increases faster than inflation. The rebate generally depends on the product’s per-unit rebate amount and the total number of units dispensed under Medicare Part D.

Federal law requires CMS to remove 340B units from Part D inflation rebate calculations beginning January 1, 2026.

CMS currently uses a claims-based Prescriber-Pharmacy Methodology to identify potentially 340B units. This methodology evaluates whether:

The prescriber NPI associated with a Prescription Drug Event is affiliated with a registered covered entity; and
The dispensing pharmacy is designated as a 340B contract pharmacy.

The new repository will allow covered entities, TPAs, and other authorized partners to submit claim-level data directly to CMS. CMS will test whether this entity-reported information can identify 340B units more accurately in the future.

For now, the repository is analytical. CMS will not use repository data to remove 340B units from Part D inflation rebate calculations unless and until CMS proposes and finalizes a policy authorizing that use.

October 1, 2026: Voluntary Enrollment Begins

The repository opens on October 1, 2026. Covered entities may voluntarily enroll and submit data for 2026 claims.

Voluntary participation gives your organization an opportunity to test:

Data availability.
Pharmacy and TPA file formats.
Covered entity ID mapping.
NDC-11 and NPI accuracy.
Internal approval workflows.
Submission corrections.
Executive certification and delegated authority.
Quarterly reconciliation processes.

CMS encourages covered entities to submit data for all 340B dispenses covered and paid for by a Medicare Part D plan with dates of service on or after January 1, 2026.

That scope applies regardless of:

Whether the drug was dispensed through an in-house or contract pharmacy.
Whether the drug is a Part D rebatable drug.
Whether a TPA identified the claim as 340B.
Whether the entity submits directly or delegates the process to a TPA or other partner.

This broad scope is one of the most important operational points in the FAQ. Do not limit your submission population only to drugs that CMS may ultimately use in an inflation rebate calculation.

What Data Must You Submit?

The CMS 340B Repository Companion Guide identifies the required claim-level fields.

Each row represents one claim and should include:

Covered entity 340B ID
Use the 340B ID associated with the claim as designated in OPAIS. If a child site does not have its own OPAIS 340B ID, the covered entity parent ID should be used.
Date of service
This is the date the prescription was filled by the pharmacy.
Prescription or service reference number
Include the unique prescription or service number assigned by the pharmacy.
Fill number
Identify whether the claim is an original fill or a refill.
NDC-11
Submit the dispensed product’s 11-digit National Drug Code using numeric characters only, including leading or trailing zeroes.
Dispensing pharmacy NPI
Submit the NPI of the pharmacy that dispensed the claim.
Claim Record Indicator
Leave the field blank for a new claim. Use “R” to remove a previously submitted claim. A corrected claim should then be submitted as a new record.

The repository accepts .xlsx and .csv files. The Companion Guide states that the file size limit is 2 gigabytes, and the fields mapped to CMS data elements must appear within the first 30 fields of the file.

Integrated pharmacy data and compliance dashboard

Correcting a Previously Submitted Claim

The repository does not allow users to edit an existing claim record directly.

If a claim requires correction, your process should be:

Resubmit the original claim data with the Claim Record Indicator set to “R.”
Submit the corrected claim as a new record using a blank indicator or “A.”
If both records are included in the same file, place the removal record before the corrected record.

This makes version control essential. Your organization should retain the original submitted data, the correction file, the reason for correction, the date of submission, and evidence of successful upload.

A correction process should be included in your written repository procedure before the first upload.

When Are Submissions Due?

CMS expects covered entities, TPAs, and other partners to submit data at least quarterly, within one calendar quarter following the close of the relevant calendar quarter. Entities may submit more frequently.

CMS’s current schedule includes the following dates:

Dates of service	Planned submission due date
January 1–September 30, 2026	December 31, 2026
October 1–December 31, 2026	March 31, 2027
January 1–March 31, 2027	June 30, 2027
April 1–June 30, 2027	September 30, 2027
July 1–September 30, 2027	December 31, 2027
October 1–December 31, 2027	March 31, 2028

Although the repository opens October 1, 2026, CMS expects covered entities to submit eligible 2026 claims retrospectively. Your entity should begin assembling January through September 2026 data before the portal opens.

A quarterly calendar should assign responsibility for:

Extracting claims.
Filtering Medicare Part D claims.
Confirming 340B status.
Validating required fields.
Reviewing exceptions.
Certifying the submission.
Uploading the file.
Retaining confirmation and audit records.

Account Creation Requires Executive Authority

The person creating the repository account must be one of the following:

The covered entity’s CEO.
The covered entity’s CFO.
An individual with authority equivalent to a CEO or CFO.
An authorized representative or contractor with delegated authority to certify on behalf of one of those individuals.

Account creation uses Login.gov, ID.me, or CMS Identity Management with Remote Identity Proofing. No CMS invitation is required. Users may access the repository website beginning October 1, 2026.

Each user should create only one repository account, even when submitting for multiple 340B IDs. A user may associate multiple 340B IDs with the account, and the list can be updated later.

The repository account is separate from the Medicare Transaction Facilitator. Even though both systems may use CMS IDM, users must complete a separate repository account process.

How TPAs and Other Partners Fit In

CMS designed the repository to accommodate organizations that use TPAs or other data partners.

A TPA may:

Create its own repository account.
Submit data on behalf of one or more covered entities.
Upload claims for multiple covered entities in a single file.
Submit claims across multiple 340B IDs in one .xlsx or .csv upload.

Each claim row must include the appropriate covered entity 340B ID for accurate attribution.

However, a TPA must have delegated authority as an authorized representative of the covered entity to submit and certify data on the entity’s behalf. That delegation should be documented through a written agreement or authorization process.

Your entity should not assume that an existing TPA contract automatically covers CMS repository certification. Review the agreement and confirm:

Who owns the submission obligation.
Who validates the data.
Who certifies the file.
Who handles corrections.
Who retains supporting records.
How errors and missed deadlines are escalated.

In-House and Contract Pharmacy Implications

The repository does not replace your existing 340B oversight responsibilities.

For in-house pharmacies, leadership should validate that pharmacy systems can identify:

Medicare Part D payment.
340B status.
Date of service.
Prescription number and fill number.
NDC-11.
Dispensing pharmacy NPI.
Covered entity 340B ID.

For contract pharmacies, the challenge may be more complex. Your entity may need to coordinate data from multiple pharmacies, TPAs, and claim-processing platforms. The fact that a TPA identifies a claim as 340B does not eliminate the covered entity’s responsibility to ensure that eligible Part D 340B dispenses are included in the reporting process.

HRSA expects covered entities to maintain oversight of contract pharmacy arrangements. Your contract pharmacy oversight process should now address repository data completeness and submission accountability as part of the broader control environment.

340B pharmacy documentation and claims management

Preparing for a Potential 2027 Mandate

In the CY 2027 Physician Fee Schedule Proposed Rule, CMS proposed requiring Medicare providers and suppliers that are 340B covered entities to submit repository data for claims with dates of service on or after January 1, 2027.

If finalized, participation would become a condition of continued Medicare enrollment. CMS proposed that failure to comply could lead to revocation of Medicare enrollment under the applicable enrollment provisions.

That requirement is not final. Nevertheless, your entity should prepare as though the process may become mandatory.

Use the following readiness framework:

1. Data readiness

Inventory every source of Medicare Part D 340B claims:

In-house pharmacy systems.
Contract pharmacy systems.
TPA platforms.
Specialty pharmacy partners.
Manual exception files.
Reversal and rebill reports.

2. File readiness

Test both accepted formats where practical:

Excel .xlsx.
Comma-separated values .csv.

Confirm that required fields are mapped correctly and appear within the first 30 fields.

3. Authority readiness

Identify the executive accountable for certification. Document any delegation to a TPA, consultant, or other authorized contractor.

4. Governance readiness

Create a written policy covering:

Reporting scope.
Quarterly deadlines.
Data validation.
Submission approval.
Corrections.
Record retention.
Escalation procedures.
TPA oversight.

5. Monitoring readiness

Track:

Claims received.
Claims excluded and the reason.
Claims submitted.
Upload confirmations.
Rejected or incomplete records.
Corrections.
Submission timeliness.

GapRx’s 340B analytics and dashboard resource explains how centralized data can improve visibility across pharmacy, vendor, financial, and compliance workflows.

What the Repository Does Not Do

The repository is distinct from the HRSA 340B Rebate Pilot. The CMS repository supports the Medicare Part D Inflation Rebate Program. It is not the HRSA rebate model.

The repository also does not change payment for 340B drugs dispensed by hospitals, clinics, in-house pharmacies, or contract pharmacies.

CMS states that submitted repository data will not be shared outside CMS. Specifically, CMS does not plan to share the data with manufacturers or Medicare Part D plans. The repository is designed as a direct, confidential connection between covered entities or their authorized partners and CMS.

What to Watch Next

The most important upcoming development is the final CY 2027 Physician Fee Schedule rule. CMS’s proposed reporting requirement could be revised, finalized, delayed, or withdrawn.

Until the final rule is published, your organization should treat 2027 reporting as a significant planning priority: but not as a final legal requirement.

Also monitor:

The CMS 340B repository user guide.
Updates to the CMS Medicare Inflation Rebate Program page.
Revised data templates.
CMS technical instructions.
Changes to the proposed enrollment provisions.
Guidance affecting Part D claim identification.
TPA and contract pharmacy implementation updates.

Final Takeaway

The CMS Medicare Part D 340B Repository opens for voluntary submissions on October 1, 2026. Covered entities should use the 2026 testing period to build a reliable reporting process for all eligible Part D 340B dispenses dating back to January 1, 2026.

Your immediate priorities are clear:

Identify all eligible in-house and contract pharmacy claims.
Confirm access to the required claim-level fields.
Assign executive or delegated certification authority.
Establish a quarterly submission calendar.
Test .xlsx and .csv workflows.
Document correction and record-retention procedures.
Coordinate expectations with TPAs and pharmacy partners.
Monitor the final CY 2027 Physician Fee Schedule rule.

The entities that treat this as a data-governance project: not just a portal upload: will be better positioned for accurate reporting, efficient corrections, and a potential 2027 mandate.

For additional context, review GapRx’s 340B rebate model timeline and contact GapRx 340B Consultants to discuss data readiness, contract pharmacy oversight, compliance controls, and program dashboards.

CMS Medicare Part D 340B Repository: What Covered Entities Must Know for October 1