To understand Medicare coverage for allergy immunotherapy, it is important to clarify the distinction between the build-up phase and dilutions of allergy extracts, as well as the reimbursement policies for each. The College’s Advocacy Council provides guidance below.
Build-up phase coverage
As previously reported, the Centers for Medicare & Medicaid Services (CMS) has confirmed there is no National Coverage Determination (NCD) governing payment for the build-up phase of allergen immunotherapy.
Coverage decisions for this phase are made by individual Medicare Administrative Contractors (MACs). As we announced previously, all seven MACs have now agreed in writing to cover the build-up phase of allergy extract preparation and administration. Additionally, five of the seven MACs – covering 38 states and three U.S. territories – have formally published Local Coverage Articles (LCAs) stating that the build-up phase for the payment for the initiation of SCIT versus the maintenance of SCIT with code CPT 95165 is not differentiated and is similarly provided as a reasonable and necessary service. These LCAs were effective Oct. 26, 2025.
Dilutions outside the build-up phase
It’s critical to distinguish the build-up phase from dilutions required outside of this initial phase. Dilutions may be necessary due to patient-specific factors, such as adverse reactions to injections or missed doses requiring a step-down in extract concentration. CMS has stated that dilutions outside the initial build-up phase are not covered and separately paid for by Medicare. Therefore, these services should not be billed to Medicare to avoid claim denials or compliance issues.
Key takeaways for providers
- Build-up phase: Covered by all MACs, with five including it in their LCAs. Ensure proper documentation and coding (e.g., CPT codes 95165 for allergen extract preparation and 95115/95117 for administration) when billing for the build-up phase. However, it is important to note that Medicare continues to assign MUEs of 30 units per day for CPT code 95165. The MUEs are the maximum unit(s) of service that can be reported for a single beneficiary on the same date of service. Claims in excess of the MUE number of units are considered “medically unlikely.” Also, Medicare continues to define a dose as 1 cc, unlike the CPT definition.
- Dilutions: Not covered by Medicare when performed outside the build-up vial set. Exercise caution and review patient records to confirm whether the service falls within the covered build-up phase.
College members should review their billing practices to ensure compliance with applicable LCAs and Local Coverage Determinations (LCDs) and to avoid potential reimbursement issues. For additional resources or guidance, please refer to the CMS website or contact AdvocacyCouncil@acaai.org. We will continue our discussions with CMS to ensure fair payment for our services and share any new developments with you promptly.
Thank you for your commitment to providing high-quality care to your patients.
The Advocacy Council – ADVOCATING FOR ALLERGISTS AND THEIR PATIENTS.
IMPORTANT: The information contained herein is provided for educational purposes only and should not be construed or relied upon as legal advice. If legal advice is required, you should seek the advice of your legal counsel.
