Bilateral Procedures and Modifiers

Published 04/28/2021

The 50 CPT modifier identifies a bilateral procedure. HCPCS modifier RT is for the right side, and HCPCS modifier LT is for the left side.

"Bilateral procedures" are defined as surgical operations performed on both the right and left side of a patient's body during the same operative session requiring separate sterile fields and a separate surgical incision. Medicare requires that when bilateral procedures are billed, they should be billed with one unit on one line with the 50 CPT modifier. The amount billed should reflect the cost of both the left and right side. Assuming that all services are medically necessary, Medicare’s allowance is 150 percent of the fee schedule for the bilateral procedures, 100 percent for one side and 50 percent for the other side. Documentation must show that the procedure was done bilaterally. If a procedure was performed twice on the same day at different sessions and/or sites, then the RT/LT HCPCS modifiers can be used but documentation must support this scenario. 

Coding claims for surgical procedures performed bilaterally depends on:

  • The HCPCS code descriptor
  • The “Bilateral Indicator” assigned to the HCPCS code, if special payment rules apply, and if it is found in the Physician Fee Schedule
  • The nature of the service

The “National Correct Coding Initiative (NCCI)” manual specifies that CPT modifier 50 is used to report bilateral surgical procedures as a single unit of service (UOS). The NCCI manual warns that MUE edits based on established CMS policies may limit units of service and are predicated on the assumption that claims are coded in accordance with these Medicare instructions. Consequently, many bilateral procedures have a MUE value of one. columns and scroll over to Bilat Surg. There will give you the bilateral indicator assigned to the code. 

Bilateral indicators only apply to the Physician Fee Schedule (PFS) and not to other Medicare payment systems. The Physician Fee Schedule is found on the CMS website

The Physicians Fee Schedule is found on the CMS website.

This will take you to the Physician Fee Schedule Search page. Fill in the drop-down details and be sure to enter the correct year and HCPCS code. Choose all modifiers and then select submit.

The Physician Fee Schedule Search page.

The page will display information about the code you entered. You need to select Show All Columns and scroll over to Bilat Surg. The bilateral indicator assigned to the code will be available in the Bilat Surg column. 

Select Show All Columns button.

Scroll over to Bilat Surg column.

Bilateral Indicators: You will usually see 0 or 1 indicators.

Bilateral Indicator

What Does the Indicator Mean


No bilateral payment adjustment. The 150 percent payment adjustment does not apply.


150 percent bilateral payment adjustment applies.


Bilateral procedure 150 percent payment adjustment does not apply. Payment is already based on the procedure being preformed as a bilateral procedure.


No bilateral payment adjustment.

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