Stem Cell Transplantation (Formerly 110.8.1) — NCD 366 | CMS Coverage Update

TL;DR: The Centers for Medicare & Medicaid Services modified NCD 366 governing stem cell transplantation coverage policy, effective January 9, 2026. Here's what billing teams need to know before submitting claims.

CMS stem cell transplantation coverage policy under NCD 366 has been updated to consolidate and clarify coverage rules for both autologous and allogeneic procedures across multiple indications. The policy does not list specific CPT or HCPCS codes in the current version, but the coverage criteria — including scoring thresholds, staging requirements, and clinical trial conditions — directly determine whether your claims pay or deny. If your facility bills for bone marrow transplants, peripheral blood stem cell transplants, or related preparatory services, this policy affects your reimbursement.

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Quick-Reference Table

Field	Detail Copy
Payer	CMS / Medicare
Policy	Stem Cell Transplantation (Formerly 110.8.1)
Policy Code	NCD 366
Change Type	Modified
Effective Date	January 9, 2026
Impact Level	High
Specialties Affected	Hematology/Oncology, Bone Marrow Transplant Programs, Inpatient Hospital Billing, Physician Billing
Key Action	Audit all active stem cell transplant claims for compliance with updated coverage criteria before submitting for dates of service on or after January 9, 2026

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CMS Stem Cell Transplantation Coverage Criteria and Medical Necessity Requirements 2026

NCD 366 is the National Coverage Determination governing Medicare coverage of stem cell transplantation, including both autologous stem cell transplantation (AuSCT) and allogeneic hematopoietic stem cell transplantation (HSCT). The policy covers procedures performed under the Inpatient Hospital Services and Physicians' Services benefit categories.

The Centers for Medicare & Medicaid Services makes one thing explicit in this update: coverage is all-or-nothing. When bone marrow or peripheral blood stem cell transplantation is covered, every step is covered — mobilization, harvesting, the transplant itself, and the administration of high-dose chemotherapy or radiotherapy beforehand. When it's not covered, none of those steps are covered either. That's a critical distinction for billing teams that might otherwise try to bill preparatory chemotherapy or mobilization services separately.

Autologous Stem Cell Transplantation (AuSCT)

AuSCT uses the patient's own previously stored cells to restore hematopoietic function after severely myelotoxic high-dose chemotherapy and/or radiotherapy. Medical necessity for AuSCT requires that the procedure is used to effect hematopoietic reconstitution following this treatment. The indication is tied to treating various malignancies — the policy doesn't enumerate every covered tumor type for AuSCT, which means your documentation needs to clearly establish that high-dose chemotherapy was required and that AuSCT was the appropriate reconstitution method.

Allogeneic HSCT — Core Covered Indications

Allogeneic HSCT coverage has multiple effective dates layered into the policy, each tied to a specific indication. Coverage has existed since August 1, 1978, for leukemia, leukemia in remission, and aplastic anemia — when the procedure is reasonable and necessary. Coverage for severe combined immunodeficiency disease (SCID) and Wiskott-Aldrich syndrome has been in place since June 3, 1985.

These longstanding indications aren't new, but they're part of the consolidated NCD 366 coverage policy. Your documentation still needs to establish medical necessity for each of these conditions individually.

Allogeneic HSCT for Myelodysplastic Syndromes (MDS)

This is one of the more complex medical necessity requirements in the policy, and it's where billing teams most often run into claim denial risk. Allogeneic HSCT for MDS is covered for Medicare beneficiaries — effective for services on or after March 6, 2024 — but only when the patient meets specific prognostic risk score thresholds using one of three recognized scoring systems:

#	Covered Indication Copy
1	IPSS (International Prognostic Scoring System): Score ≥ 1.5 (Intermediate-2 or high risk)
2	IPSS-R (Revised International Prognostic Scoring System): Score ≥ 4.5 (high or very high risk)
3	IPSS-M (Molecular International Prognostic Scoring System): Score ≥ 0.5 (high or very high risk)

The policy accepts any one of these three systems — you don't need all three. But the score must be documented in the medical record before billing. If your physician documentation doesn't include the specific IPSS, IPSS-R, or IPSS-M score, you have a medical necessity problem, not a billing problem. Fix it upstream.

Allogeneic HSCT for Multiple Myeloma

For multiple myeloma, allogeneic HSCT is covered only under specific conditions. Effective for claims with dates of service on or after January 27, 2016, coverage requires the beneficiary to have Durie-Salmon Stage II or III multiple myeloma, or International Staging System (ISS) Stage II or Stage III multiple myeloma. Beyond staging, the beneficiary must be participating in an approved prospective clinical study.

This is a prior authorization–adjacent requirement. There's no standard prior auth process here, but the clinical trial participation requirement functions as a gatekeeping mechanism. If your patient isn't enrolled in an approved study, the claim won't pay — regardless of staging.

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CMS Stem Cell Transplantation Exclusions and Non-Covered Indications

The policy is explicit: when a bone marrow or peripheral blood stem cell transplantation is non-covered, none of the component steps are covered. That means mobilization agents, apheresis, conditioning chemotherapy, and the infusion itself all fall outside coverage if the underlying transplant indication isn't covered.

For multiple myeloma specifically, allogeneic HSCT outside of an approved clinical trial is non-covered for Medicare beneficiaries. This is a hard line. Document trial enrollment before you bill.

The policy also notes that coverage determinations are based on what is "reasonable and necessary" — the standard Medicare medical necessity threshold. Claims that lack documentation tying the procedure to a covered indication, with appropriate clinical criteria, face denial on medical necessity grounds.

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Coverage Indications at a Glance

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CMS Stem Cell Transplantation Billing Guidelines and Action Items 2026

The effective date of January 9, 2026 is your line in the sand. Here's what your billing team needs to do now.

Copy Action Items

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CPT, HCPCS, and ICD-10 Codes for Stem Cell Transplantation Under NCD 366

The current version of NCD 366 does not list specific CPT, HCPCS, or ICD-10 codes within the policy document. This is not unusual for NCDs — coverage is determined by indication and clinical criteria, not by a defined code list.

That said, stem cell transplantation billing typically involves procedure codes for bone marrow harvesting, peripheral blood stem cell apheresis, transplant infusion, and high-dose conditioning regimens. Your Medicare Administrative Contractor (MAC) may issue a Local Coverage Determination (LCD) or billing guidance that maps NCD 366 criteria to specific codes for your region. Check with your MAC if you need code-level guidance that aligns with this coverage policy.

Your coding team should also verify ICD-10-CM diagnosis codes for MDS, leukemia, aplastic anemia, SCID, Wiskott-Aldrich syndrome, and multiple myeloma are accurate and specific to the documented indication. Diagnosis code precision is what ties a claim to a covered indication under NCD 366 — and it's what survives an audit.

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