When is it appropriate to use modifier 90?

Reference (Outside) Laboratory

When laboratory procedures are performed by a party other than the treating or reporting physician, the procedure may be identified by adding the modifier 90 to the usual procedure number.

Modifier 90 should be appended to the procedure code representing the laboratory service that is being submitted to an outside laboratory for processing in lieu of being processed within the practice or clinic of the treating/reporting physician or other qualified health care professional. Typically, the clinician reports the laboratory service but the actual testing occurs at an outside laboratory.

Correct Use

• Outside laboratory performs procedure, unrelated to treating/reporting physician
  • In most cases, lab furnishing the service would bill the claim
• Possible for one lab to bill service performed by another lab
  • Referring = referring specimen to another laboratory for testing
  • Reference = lab that receives specimen from another lab and performs one or more tests on such specimen
• Must append modifier 90 to referred laboratory test code
  • Item 20 mark “Yes” = outside lab
  • Purchase price must be reflected under charges
  • Complete item 32 with NPI, name and address where performed
• Appropriate modifier 90 claims include two different Clinical Lab Improvement Amendment (CLIA) numbers
  • Reflect billing provider information
  • Laboratory where services were performed (reference lab)
•     Bill claims with modifier 90 and without modifier 90 separately
•     If no purchased services, leave item 20 blank

Do not Use Modifier 90 in below cases:

• Do not report modifier 90 with anatomic pathology and lab services
• Do not append modifier 90 for drawing fee (36415)
  • Cannot be referenced out to another lab

Modifier 90 is used by a physician or clinic when the laboratory tests performed for a patient are performed by an outside or reference laboratory. This modifier is used to indicate that although the physician is reporting the performance of a laboratory test, the actual testing component was a service from a laboratory.

• Modifier 90 (reference laboratory) will not bypass clinical edits, subsets, bundling, etc.
• If some of the blood and/or serum lab procedures are performed by the provider and others are sent to an outside lab and billed with modifier 90, CPT 36415 is not eligible for separate reimbursement.
• CPT codes 99000 and 99001 (handling fees) are not eligible for separate reimbursement

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