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Modifier 90

Modifier 90 Description and Billing Use

Plain-language description

Reports a laboratory test performed by an outside or reference laboratory when applicable.

How modifier 90 is used

Modifier 90 identifies a laboratory test performed by an outside or reference laboratory. The billing entity should retain the order, result, performing-laboratory identity, and information required by the payer and claim format.

Before reporting this modifier

  1. 1. Confirm the current official or licensed definition and payer acceptance.
  2. 2. Identify the exact claim circumstance the modifier communicates.
  3. 3. Make the code, setting, related services, and medical record consistent.
  4. 4. Check NCCI, global surgery, component, DME, ABN, or drug rules that apply.
  5. 5. Do not append a modifier only to force an edit override.
LessonStudy the related billing ruleOfficial sourceReview current CMS guidance

This is a workflow summary, not a licensed CPT definition or claim-specific coding instruction. Verify the code set and payer rule effective for the date of service.