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    v1.0.30
    OpenPayerPolicy UpdatesReimbursement/Payment PolicyWellpoint Modifier 90/91 Coverage Update | OpenPay…
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    CurrentWellpointPolicy G-20001

    Modifiers 90 and 91: Laboratory Services

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    This policy governs reimbursement for laboratory services billed with modifiers 90 and 91 on professional and outpatient facility claims in Tennessee Medicaid.

    Policy Summary
    PayerWellpoint
    PolicyModifiers 90 and 91: Laboratory Services
    Policy CodePolicy G-20001
    Change TypeMaterial revision
    Effective DateFeb 1, 2027
    Next Review DateNot specified
    Key ActionBill laboratory services to the provider or outpatient facility that performed the test; do not use pass-through billing.
    SourceLink
    POLICY UPDATE CHANGES

    The prior standalone modifier 91 policy was retired and its requirements were combined with modifier 90 guidance in a blended laboratory services policy.

    90Modifier 90 claims are not eligible for pass-through laboratory billing
    91Modifier 91 repeat tests may be reimbursed when appropriately reported
    100%Applicable fee schedule or contracted/negotiated rate
    1 unitMaximum reimbursable units when only one unit is permitted

    OpenPayer is powered by Trek Health's payer performance platform. Trek continuously ingests, validates, and normalizes Transparency in Coverage data alongside payer policies and other commercial payer data to create a structured payer intelligence foundation. OpenPayer uses this foundation to deliver personalized search results, dynamically generated policy pages, and tailored policy monitoring based on each user's payers, specialties, billing codes, and areas of interest. The same intelligence powers broader payer performance workflows, including reimbursement benchmarking, contract evaluation, payer negotiations, and financial decision-making.

    Modifier 90 and 91 Coverage Criteria

    Modifier 90: Reference laboratory services

    Not eligible for reimbursement when all of the following apply:

    ALL of the following

    • The laboratory service is billed on a professional or outpatient facility claim with modifier 90.
    • The provider or outpatient facility billing the service did not perform the laboratory test.

    Modifier 91: Repeat clinical diagnostic laboratory tests

    May be separately reimbursed when all applicable criteria are satisfied:

    ALL of the following

    • The same clinical diagnostic laboratory test was performed more than once on the same patient on the same day.
    • The repeat testing was necessary during the course of treatment to obtain subsequent multiple test results.

    • ALL of the following

      • The repeat test was not performed only to confirm an initial result.
      • The repeat test was not performed because of specimen or equipment problems.
      • A normal, one-time, reportable result was not all that was required.
      • Another code does not describe a series of test results, such as glucose tolerance or evocative/suppression testing.
    • Medical documentation supports appropriate use of modifier 91 when requested.

    Billing and Reimbursement Coding

    Modifier 90ModifierNot Covered
    90Reference (Outside) Laboratory modifier
    Modifier 91ModifierCovered
    91Repeat Clinical Diagnostic Laboratory Test modifier
    Same-day repeat testing
    Test frequencyThe laboratory test must be performed more than once on the same day.
    Patient requirementThe repeated test must be performed on the same patient.
    PurposeThe repeat testing obtains subsequent multiple test results during treatment.
    Multiple-unit reimbursement
    Multiple units billedThe procedure code is billed with multiple units.
    Payment limitationOnly one unit is permitted.

    Provider Billing Actions

    Billing Rule

    Do not use modifier 90 for pass-through billing

    Bill laboratory services to the provider or outpatient facility that performed the test; do not use pass-through billing. Claims appended with modifier 90 will not be eligible for reimbursement, except for pathology services reported with modifier 90 when billed by pathology providers.

    Documentation Required

    Support appropriate repeat testing with modifier 91

    Use modifier 91 only when the same clinical diagnostic laboratory test is performed more than once on the same patient on the same day to obtain subsequent multiple test results during treatment. Maintain medical documentation supporting appropriate use because it may be requested.

    Key Definitions

    Pass-Through Billing
    Who pays the laboratoryA provider, such as a physician or hospital, pays a laboratory to perform the tests.
    Who performs the testsThe laboratory performs the tests for the provider.
    Claim submissionThe provider then files the claims as though the provider performed the tests itself.
    Repeat Clinical Diagnostic Laboratory Test
    Test performedThe same laboratory test is performed more than once.
    Timing and patientThe repeat test is performed on the same patient on the same day.
    Clinical purpose
    Policy Summary
    PayerWellpoint
    PolicyModifiers 90 and 91: Laboratory Services
    Policy CodePolicy G-20001
    Change TypeMaterial revision
    Effective DateFeb 1, 2027
    Next Review DateNot specified
    Key ActionBill laboratory services to the provider or outpatient facility that performed the test; do not use pass-through billing.
    SourceLink
    On This Page
    Modifier 90 and 91 Coverage CriteriaBilling and Reimbursement CodingProvider Billing ActionsKey Definitions
    Reimbursement basis
    Reimbursement is based on a single unit.
    Reimbursement rate
    Reimbursement amount100% of the applicable fee schedule or contracted/negotiated rate.
    Modifier 90 servicesReimbursement is made directly to the provider that performed the clinical diagnostic laboratory test.
    Modifier 91 servicesRepeat clinical diagnostic laboratory tests appended with modifier 91 are reimbursed at 100% of the applicable fee schedule or contracted/negotiated rate.
    Denial Risk

    Avoid inappropriate modifier 91 use

    Do not use modifier 91 when only one test result is required, when a test is rerun to confirm an initial result, or because of specimen or equipment problems. The modifier is also inappropriate when another code describes a series of test results or the service is otherwise not an appropriate repeat clinical diagnostic laboratory test.

    Billing Rule

    Prevent duplicate-service denial

    Report modifier 91 for repeat clinical diagnostic laboratory tests rather than billing the repeated test as an unmodified duplicate service. Failure to use the modifier appropriately may result in denial of the repeated laboratory test as a duplicate service.

    The repeat testing obtains subsequent multiple test results during treatment.