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About the Claims Process

Understanding Vaccine Coverage

Private insurance, the Health Insurance Marketplace, and a number of government programs provide coverage and will pay for immunizations. Below are the reimbursement pathways you and your staff may expect to encounter when processing immunization claims.

The majority of commercially available health plans fall under the Affordable Care Act (ACA). Under the ACA, preventive services include coverage for immunizations approved by the Advisory Committee on Immunization Practices (ACIP) at an in-network provider with $0 out of pocket.

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Medicare Part B-Medical Benefit:

  • Medicare Part B covers immunization for influenza, pneumococcal disease, and hepatitis B for those patients defined as medium or high risk1
  • Medicare Part B also covers the tetanus vaccine (and other tetanus vaccine preparations that include diphtheria or pertussis components), when administered as part of a therapeutic regimen following an injury2

Medicare Part D—prescription drug/pharmacy benefit

  • ACIP-approved adult immunizations must be covered by all Medicare Part D plans, unless they are covered under Medicare Part B1
  • For patients with Medicare Prescription coverage as of January 1, 2023, Part D-covered adult vaccines recommended by the Advisory Committee on Immunization Practices (ACIP) will be available at $0 out of pocket with no deductible and no cost-sharing9

Some ACIP-approved adult immunizations for patients aged 19 and older are covered under the Medicaid medical benefit, if the state Medicaid program is an expansion program. For patients with a managed Medicaid plan, ACIP-approved adult immunizations are covered if administered at an in-network provider.3

For Medicaid patients under the age of 19, vaccines covered by Vaccines for Children (VFC) are expected to be used.4  

TIP: Check with your local Medicaid office to find the administration fee for your state.

Mother with child photo

VFC is a federally funded program that provides vaccines to eligible children and adolescents whose families cannot otherwise afford immunization services.4 Eligible children are those who are younger than 19 and either Medicaid-eligible, uninsured, underinsured, or an American Indian or Alaskan Native.4

VFC-registered providers administer the vaccines through this program as follows:

  • Eligible patients receive vaccines free of charge, as vaccine products have already been paid for with federal tax dollars5
  • The provider may charge families/caregivers of eligible patients an administration fee for VFC vaccines5
    • Administration fees vary by state and are based on a regional scale determined by the Centers for Medicare and Medicaid Services (CMS)5
    • Administrative fees represent the maximum amount that providers may charge for each vaccine administered. Providers have the option to charge what they feel is fair, including no charge at all, without exceeding this maximum5
  • VFC vaccines can be administered by any enrolled VFC provider (private doctor, private clinic, hospitals, public health clinic, community health clinic, schools, etc.)5

There are many other federally and state-funded programs that provide vaccines at no cost.

  • Providers may not bill or attempt to obtain payment for "free" vaccines5
  • Some insurers may require providers to append a modifier (eg, “SL”, which indicates the vaccine is state-supplied) to the vaccine or toxoid code to designate its "free" status6,7
  • In some instances, administration fees may also require modifiers (eg, “SA”, which indicates service provided by a nurse practitioner)8
Doctor speaking with patient photo

For state health department phone numbers, go to

For a comprehensive, up-to-date directory of immunization resources, go to

TIP: You must check the payer’s guidelines for documenting vaccines obtained at no cost ("free") before submitting claims for administering such immunizations.

Diagnosis Codes

Z23 is the ICD-10-CM code used when reporting an encounter for immunization for all vaccines given within the encounter. In some instances, additional ICD-10-CM coding may be needed.

See all code types


Find answers to frequently asked questions, along with additional resources, to guide you to the information you need. 

Get help


  1. Medicare and you 2023: The official U.S. government Medicare handbook. Centers for Medicare & Medicaid Services. Accessed January 19, 2023.
  2. Tetanus and diphtheria vaccinations billing guidelines. Noridian Healthcare Solutions. Updated December 9, 2022. Accessed January 19, 2023.
  3. How to pay. U.S. Department of Health and Human Services. Reviewed April 29, 2021. Accessed January 19, 2023.
  4. Vaccines for Children Program (VFC): About VFC. Centers for Disease Control and Prevention. Reviewed February 18, 2016. Accessed January 19, 2023.
  5. Vaccines for Children Program (VFC): VFC detailed questions and answers for parents. Centers for Disease Control and Prevention. Reviewed December 17, 2014. Accessed January 19, 2023.
  6. Vaccines for Children policy, professional. United Healthcare Community Plan. Proprietary information of UnitedHealthcare Community Plan. Copyright 2023 United HealthCare Services, Inc. 2023R7109A. Accessed January 19, 2023.
  7. Vaccine and immunization. Harvard Pilgrim Health Care. November 2022. Accessed January 19, 2023.
  8. ACA increases reimbursement for primary care services in 2013 and 2014. IHCP Bulletin. Indiana Health Coverage Programs. November 27, 2012. Accessed January 19, 2023.
  9. The Inflation Reduction Act Lowers Health Care Costs for Millions of Americans. Fact Sheet. Centers for Medicare and Medicaid Services. October 5, 2022. Accessed January 19, 2023.

Appealing Denial of Insurance Claims

The Affordable Care Act (ACA) gives everyone the right to ask insurers to reconsider a denied claim or appeal their decision. When a health plan conducts a review of an appealed claim, the process is referred to as an "internal appeal." In the event that the plan denies the appeal, the ACA allows for an independent review organization to conduct an "external review" and either uphold the health plan's decision or overturn it.1

After checking your contract, if you believe a claim has been improperly reimbursed or denied, you may consider submitting an appeal.

Before beginning a formal appeal process, you should first do the following:

  • Review the Remittance Advice/Explanation of Benefits (EOB) to identify any remark codes that may identify a reason for denial
  • Check for any coding errors, including CPT codes, NDCs, units, etc. If the denial was due to a coding error, consider filing a corrected claim as opposed to an appeal

If you still have not found a reason for denial, call the health plan to verify eligibility and reimbursement amounts. Be prepared to provide the health plan with the claim number and all the information on the original claim that was not paid for or not paid correctly. You may also need to provide the health plan with the employer name and/or group number.

If you are still not satisfied after calling the health plan, you may consider filing a letter with the health plan that includes the original claim. Be sure to check with your individual payers’ guidelines—claims may only be eligible for appeal for a limited amount of time.

Diagnosis Codes

Z23 is the ICD-10-CM code used when reporting an encounter for immunization for all vaccines given within the encounter. In some instances, additional ICD-10-CM coding may be needed.

See all code types


Find answers to frequently asked questions, along with additional resources, to guide you to the information you need.

Get help


  1. Affordable Care Act: Working with states to protect consumers. Centers for Medicare & Medicaid Services. Accessed January 19, 2023.

Please note that this website is provided for informational purposes only and is not intended to serve as comprehensive training on medical billing and coding. Additional training on medical coding may be required. The information on this website is believed to be accurate as of the date of publication. Users should independently verify accuracy.

Healthcare providers are responsible for making the ultimate decision on when to use a specific product based on clinical recommendations and how to bill for products and related services rendered. Consult third-party insurers' guidelines for specific information regarding the billing and reporting of services rendered.