Modifier LT: Left side
When it is appropriate
Append LT to identify that a procedure was performed on the left side of a paired organ or structure, including to bypass an NCCI PTP edit when the column one and column two codes were performed on opposite sides of the body during the same session.
When it is not appropriate
Do not use LT when the procedure is on a midline structure with no left or right distinction, or when both procedures were actually performed on the same side, since that does not support separate payment.
CMS preference
LT (with RT) is one of the anatomic modifiers CMS explicitly lists as able to bypass an NCCI PTP edit when the two codes were performed on genuinely different sides.
Retrieved 2026-07-18.
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DenialPath provides billing and administrative guidance based on published CMS and X12 sources. It is not medical advice, not a coverage determination, and not a guarantee of payment. NCCI and MUE edits are republished quarterly and payer policies vary by contract. Always confirm against the payer's own current policy before submitting or appealing.