Non-Billable / Non-Specific Code
ICD-10-CM Z28.3 is the diagnosis code for Underimmunization status. This code falls under the section "Persons with potential health hazards related to communicable diseases" within Chapter 21 — Factors influencing health status and contact with health services (Z00-Z99). It is a non-billable/non-specific ICD-10-CM code that should not be used for reimbursement. A more specific sub-code is required for billing. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
Always refer to the official ICD-10-CM Tabular List for complete coding guidelines. Ensure documentation supports the specificity of the code selected. When in doubt, consult a certified medical coder or the latest CMS guidelines.
Understanding where Z28.3 sits in the ICD-10-CM classification helps ensure proper coding:
No, Z28.3 is a non-billable/non-specific code. You should use a more specific sub-code for billing and reimbursement.
Z28.3 is the ICD-10-CM diagnosis code for "Underimmunization status". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
The parent code of Z28.3 is Z28 ("Immunization not carried out and underimmunization status"). Z28.3 provides a more specific classification within this category.
Z28.3 is located in Section Z20-Z29 — "Persons with potential health hazards related to communicable diseases" within Chapter 21 of the ICD-10-CM Tabular List.
Z28.3 has 2 sub-code(s) that provide more specific detail: Z28.31, Z28.39.
Use Z28.3 when the patients documented diagnosis matches "Underimmunization status" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Underimmunization status is Z28.3.
No, Z28.3 is non-billable. Use a more specific sub-code for primary diagnosis billing.
Z28.3 is in Chapter 21 of the ICD-10-CM Tabular List.
Yes, Z28.3 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.