Modifier 90; Reference (Outside) Laboratory

Policy No: 118
Originally created: 12/01/2021
Section: Modifiers
Last Reviewed: 03/01/2024
Last Revised: 03/01/2023
Approved: 03/14/2024
Effective: 04/01/2024

This policy applies to physicians and other qualified health care professionals.


Modifier 90
Modifier 90 is appended to a procedure code to identify laboratory procedures performed by a party other than the treating or reporting physician or other qualified health care professional.

Pass-through Billing
When a provider pays a laboratory to perform a lab test then files a claim for reimbursement of these services.

Policy statement

Our Health Plan does not allow pass-through billing for laboratory services.

  • Laboratory services identified as being pass-through billing, without the use of modifier 90, are subject to review.
  • Laboratory services billed with modifier 90 will only be reimbursable when billed by independent laboratories, unless State, Federal or Centers for Medicare & Medicaid Services (CMS) contracts and/or requirements indicate otherwise.

Only independent clinical laboratories can refer laboratory services to another laboratory. Our Health Plan will directly reimburse independent laboratories that perform clinical diagnostic laboratory tests, based on any applicable fee schedule or contracted/negotiated rate.

A valid Federal Clinical Laboratory Improvement Amendments (CLIA) Certificate Identification number is required for reimbursement of clinical laboratory services.

Laboratory tests must be performed by, and billed by, a laboratory participating with our health plan. The use of non-participating laboratories may subject our members to unnecessary services not ordered by the treating provider, or other unreasonable financial exposure. In such circumstances, we may hold the treating or referring provider financially liable for any services deemed to be not medically necessary or non-reimbursable, if the treating or referring provider referred the specimen or member to the non-participating laboratory.


American Medical Association. Appendix A: Modifiers, Current Procedural Terminology (CPT®). AMA Press

Centers for Medicare & Medicaid Services (CMS), Medicare Claims Processing Manual, Chapter 16 Laboratory services

Noridian Medicare, Modifier 90

Cross References

Urine Drug Testing


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