Correct Use of Laterality Modifiers

Correct use of laterality modifiers supports clear and accurate reporting when a procedure is performed on the right side, left side, or on both sides of the body. CMS guidance indicates that these modifiers should be applied when appropriate. Modifiers include:

  • RT appended when procedures performed on the right side
  • LT appended when procedures performed on the left side
  • 50 appended when procedure is performed bilaterally

Additional anatomic modifiers are available for:

  • Eye lids - E1-E4
  • Fingers - F1-F9, FA
  • Toes - T1-T9, TA
  • Coronary arteries - LC, LD, LM, RC, RI

CMS Guidance

According to the CMS Internet Only Manual (IOM), Publication 100-04, Medicare Claims Processing Manual, Chapter 4, Section 20.6.3, modifiers LT and RT apply to codes that identify procedures that can be performed on paired organs, such as, ears, eyes, nostrils, kidneys, lungs, and ovaries. These modifiers should be used whenever a procedure is performed on only one side. When a procedure is performed bilaterally, the appropriate bilateral modifier should be appended.

Bilateral procedure modifier 50 is used to report bilateral procedures that are performed on both sides of the body at the same operative session (may not be paired organs). Do not report modifiers RT and LT when modifier 50 applies. Only submit one line item to report a bilateral procedure using modifier 50 and one unit of service.

Example: major joint injection performed in right shoulder and left knee. CPT code 20610 is performed on both sides of the body, modifier 50 would apply.

NCCI Guidance

The National Correct Coding Initiative (NCCI) Policy Manual, Chapter 1, also provides direction on the proper use of anatomic modifiers. Some CPT codes limit the number of times a procedure may be reported. In these cases, laterality modifiers supply essential information by indicating which side of a paired organ or structure was treated, ensuring accurate claim processing and compliance with coding guidelines.

Modifier guidance is available on Noridian’s Browse by Topic, Modifiers webpage.

Last Updated Feb 19 , 2026