Skip to Main Content
 
 
 
Web Content Viewer

Policy Education Topics

Web Content Viewer
Web Content Viewer

Modifier 90 (Reference to Outside Laboratory)

The 90 modifier is to be used when the billing laboratory refers a specimen to another lab for testing. In these cases, the billing lab is titled the “referring lab” while the lab that actually performed the test is the “reference lab.”

  • Only independent billing clinical laboratories (specialty 69) can bill with the 90 modifier. Sometimes a clinical diagnostic independent lab, place of service (POS) 81, refers a specimen to another lab for testing, where a modifier 90 is appended.
    • The billing entity must be designated as a specialty 69 in their provider enrollment record within the Provider Enrollment, Chain, and Ownership System (PECOS).
  • 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 test was performed
  • Appropriate modifier 90 claims include two different Clinical Lab Improvement Amendment (CLIA) numbers on electronic claims
    • Reflect billing provider information
    • Laboratory where services were performed (reference lab)
  • Bill claims with modifier 90 and without modifier 90 separately electronically on the same claim
  • If no purchased services, leave item 20 blank
  • When the lab submits claims, services both performed and referred may be billed on the same electronic claim. Regardless, of the services performed, whenever the 90 modifier is billed on a claim, the following information must be included.
Information Loop Field Identifier
Billing lab’s CLIA number 2300  REF02 X4
Reference lab’s CLIA number 2400 REF02 F4
Modifier 90 (Reference to Outside Laboratory)
Web Content Viewer
Web Content Viewer
Complementary Content