What does Modifier 90 signify in billing?

Modifier 90 indicates that the procedure involves the use of an outside laboratory for testing. This modifier is used primarily in situations where a healthcare provider orders laboratory tests that are conducted by a separate entity rather than the provider's in-house lab. By using Modifier 90, it clarifies that the provider is billing for the service but is reporting that the tests were not performed in their facility, thus allowing for proper allocation of services and accurate billing practices.

This modifier helps ensure that the financial responsibility for the laboratory services is transparent and appropriately allocated to the correct provider or facility, which is crucial for accurate healthcare billing. It also aids payers in understanding the origin of the laboratory services involved in the patient's care and the separation of in-house versus outsourced procedures.