-LT

Modifier -LT: Left side (laterality modifier)

Quick reference

• Definition: HCPCS modifier **-LT**means left side of the body and is used to identify procedures/items performed/provided on the left side.
• What it impacts: -LT generally does not change the allowed amount by itself, but missing a required laterality modifier can trigger denials or development.
• Paired modifier: -RT identifies the right side and is used in the same way when laterality is required.

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Most common uses

• Unilateral service on a paired organ/structure: Append -LT when a service is performed only on the left member of a paired anatomy (e.g., left eye/left ear/left nasal structure when payer requires laterality).
• Clarity + claim edits: Use -LT to make the claim’s laterality explicit when the body has left/right parts and the service is performed on the left side.
• Bilateral via two lines (payer-dependent): Some payers require bilateral reporting as two separate lines (one with -LT and one with -RT), each with 1 unit.

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Medicare billing rules (high yield)

• Don’t combine -LT/-RT with -50 when -50 applies: CMS states LT and RT shall not be reported when the -50 modifier applies.
• If billing bilateral using RT/LT lines: Noridian’s instruction is to bill bilateral usage as two separate claim lines using RT and LT with one unit of service on each line.
• Avoid inherently bilateral descriptors: If the procedure code description specifies bilateral or a specific side, laterality modifiers are not appropriate.

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Documentation checklist

• State laterality in the note: Document “left” (and the specific structure, e.g., left eye/left ear) in the assessment and procedure note so the -LT modifier is clearly supported.
• Match claim to documentation: If you append -LT, the note should not read “OU/bilateral/both” without clarifying what was actually done on the left side.
• Use correct bilateral approach: If the record supports a true bilateral service, choose either -50 (when appropriate) or two-line RT/LT reporting based on payer/MPFS rules—don’t mix approaches on the same line.

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Specialty examples (ophthalmology + ENT)

• Ophthalmology: If a unilateral eye procedure is performed on the left eye, report the procedure with -LT when the payer requires laterality on the claim line.
• ENT: If a unilateral ear/nasal procedure is performed on the left side, use -LT to identify the side when the code is side-appropriate and laterality is required.
• Bilateral same session: If the same eligible procedure is performed on both sides, follow Medicare/payer guidance—either bill -50 (if applicable) or bill RT and LT on separate lines with 1 unit each (payer-specific).