Published Date: 2025-08-20

Coding Corner: Flu Vaccinations for Medicare Beneficiaries

Flu vaccination is a critical preventive service covered under Medicare Part B, with no out-of-pocket cost to beneficiaries when provided by enrolled providers. To ensure accurate reimbursement and compliance with Medicare guidelines, it's essential to understand how to properly report flu vaccine services using the correct CPT and ICD-10-CM codes.

CPT Coding for Influenza Vaccinations

Flu vaccine reporting requires two components: the administration code and the vaccine product code. These must be billed together unless the vaccine is provided free of charge (e.g., through a public health program).

Administration Code (always required):

G0008 – Administration of influenza virus vaccine (not administered in home).
M0201 - Administration of influenza vaccine, as well as pneumococcal, hepatitis B, or COVID-19 vaccine, inside a patient’s home; reported only once per individual home per date of service when such vaccine administration(s) are performed at the patient’s home.

Vaccine Product Codes (select appropriate based on formulation):

The Centers for Medicare & Medicaid Services (CMS) updates covered flu vaccines annually. Some of the most commonly reported flu vaccine CPT codes include:

90662 – High-dose quadrivalent flu vaccine (for patients 65 and older; most commonly used in Medicare population).
90653 - Influenza vaccine, inactivated (IIV), subunit, adjuvanted, for IM use.
90656 - Influenza virus vaccine, trivalent (IIV3), split virus, preservative free, 0.5 mL dosage, for IM use.
90657 - Influenza virus vaccine, trivalent (IIV3), split virus, 0.25 mL dosage, for intramuscular use.
90674 – Quadrivalent, preservative-free, prefilled syringe.
90686 – Quadrivalent vaccine, standard dose.
90756 – Cell-based quadrivalent flu vaccine.

Note: Always check the current coding and reporting updates CMS Influenza Vaccine Pricing List for coverage.

ICD-10-CM Diagnosis Codes

To bill flu vaccines under Medicare, an appropriate ICD-10-CM diagnosis code must be included. The diagnosis code indicates the reason for the encounter and must support the medical necessity for vaccination. The ICD-10-CM Code is:

Z23 – Encounter for immunization.

This is the universal diagnosis code used for all vaccines, including the flu shot. It indicates that the service is preventive in nature and is typically the only diagnosis code required when billing flu vaccinations.

Do Not Report diagnosis codes for respiratory conditions like J09–J11 (influenza), unless you are treating the condition. These are not appropriate for preventive flu vaccination claims.

Example Claim for Medicare Beneficiary:

If a 70-year-old patient receives a high-dose flu vaccine during a visit, the billing should look like this:

Diagnosis Code: Z23
Procedure Codes:
G0008 – Administration of influenza vaccine.
90662 – High-dose flu vaccine.

Tip: If the flu vaccine is provided during a visit where other services are rendered (e.g., a problem-focused E/M visit), use modifier -25 on the E/M code to indicate that it was a significant, separately identifiable service. Thorough documentation in the patient's medical record is crucial to justify the use of modifier -25. It should clearly demonstrate the medical necessity of the E/M service and its separation from the other procedure.

Important Medicare Billing Tips:

No copay, coinsurance, or deductible applies when reporting flu vaccines under Medicare Part B.
Do not report flu vaccines under Medicare Part D; it’s always covered by Part B.

Check out next month’s Provider News for a closer look at reporting and coding the flu vaccination for Medicaid patients.

References
CMS. (2025, June 10). Flu Shot. Retrieved from CMS.GOV: https://www.cms.gov/flu-provider