HCPCS Modifier LT

What modifier LT means

Modifier LT is a laterality modifier indicating a procedure was performed on the left side of a paired anatomic structure. It is informational and helps prevent duplicate-claim edits when the contralateral side is also reported.

When to use it

A procedure on a left-sided paired structure — for example, a left knee injection or a procedure on the left eye.

Documentation checklist

The record should support every item below before you append modifier LT.

• The left-side laterality noted in the procedure record
• The specific anatomic structure treated

Do NOT use modifier LT when

• A true bilateral procedure is performed — use modifier 50 (per the payer's bilateral rules)
• The structure is non-paired or midline
• The payer requires modifier 50 formatting instead of LT/RT

Common denial reasons

• LT/RT used where the payer expects modifier 50
• Laterality conflicts with the diagnosis (e.g., right-sided ICD-10 with LT)
• Duplicate edit when both sides are billed without distinct laterality lines

How to appeal a modifier LT denial

Ensure the laterality matches the diagnosis and resubmit with LT for the left-sided service; if billed bilaterally, confirm whether the payer wants LT/RT on two lines or modifier 50 on one line and reformat accordingly.

Payer notes

For bilateral services, some payers want LT and RT on two lines while others want one line with modifier 50 — formatting varies. LT/RT are frequently required on DMEPOS and imaging claims.

Related & commonly confused modifiers

Where modifier LT is used

• Surgery on paired structures
• Radiology
• Injections (e.g., 20610) and DMEPOS