Modifier RT- Right Side

Identifies that a procedure or service was performed on the right side of the body when laterality is relevant to accurate claim reporting and reimbursement.

What Is Modifier RT?

Modifier RT is a HCPCS Level II anatomical modifier defined as “Right side.” CMS describes it as identifying procedures performed on the right side of the body.

It is appended to an applicable CPT or HCPCS code when a procedure or service is performed on a paired organ, extremity, or other anatomical structure on the patient's right side.

Its counterpart is Modifier LT, which identifies the left side.

RT provides important laterality information to Medicare and other payers and can also play a role in determining whether procedures performed at separate anatomical sites qualify for separate reporting.

CMS's 2026 NCCI Policy Manual recognizes RT and LT as anatomical modifiers that may be used with NCCI Procedure-to-Procedure edits when the clinical circumstances legitimately support separate anatomical sites.

When to Use Modifier RT

Right-Sided Procedure: The procedure or service is performed specifically on the patient's right side.

Paired Anatomical Structure: The service involves an organ, extremity, or other structure that has distinct right and left sides.

Payer Requires Laterality: Medicare or another payer requires RT to identify the anatomical side where the service occurred.

Separate Anatomical Site: RT may distinguish a service performed on a right-sided structure from another service performed at a separate anatomical site.

NCCI Requirements Are Met: RT may be used as an NCCI-associated anatomical modifier when services are legitimately performed at separate anatomical sites and the applicable edit permits modifier use.

Documentation Supports the Right Side: The medical record clearly identifies the right side as the site of the procedure or service.

When NOT to Use Modifier RT

Left-Sided Service: Use Modifier LT when the service is performed exclusively on the left side.

No Laterality Exists: Do not append RT when the procedure involves an anatomical structure or service without a meaningful right-versus-left distinction.

Code Already Provides Required Specificity: RT may be unnecessary when the procedure code itself provides sufficient anatomical specificity and the payer does not require an additional modifier.

Documentation Is Unclear: Do not infer the right side when laterality is absent or inconsistent in the medical record.

To Bypass an NCCI Edit: RT cannot be appended simply to override an NCCI edit. CMS requires the clinical circumstances to justify use of the modifier.

Bilateral Reporting Requires Another Method: Do not automatically submit separate RT and LT lines when Medicare or another payer requires Modifier 50 or another bilateral reporting method.

Billing Example

A physician performs an eligible procedure on a patient's right knee.

The procedure note clearly documents the right knee as the treatment site.

The physician reports the applicable CPT or HCPCS procedure code with Modifier RT to communicate that the procedure was performed on the right side.

If the procedure had been performed only on the left knee, LT would generally identify the left side.

If the same qualifying procedure were performed bilaterally, the provider would need to determine whether the applicable code, setting, and payer require Modifier 50 or separate RT and LT reporting.

Documentation Requirements

Laterality: Clearly document that the service was performed on the right side.

Anatomical Site: Identify the specific right-sided organ, extremity, or structure involved.

Procedure Performed: Document the procedure or service performed at that anatomical site.

Medical Necessity: Support the clinical reason the procedure or service was necessary.

Consistent Documentation: Orders, operative reports, procedure notes, imaging reports, and other relevant records should consistently identify the right side.

Multiple Sites: When multiple anatomical locations are treated, clearly document which procedure was performed at each site.

Billing and Claim Considerations

Modifier RT supplies anatomical information. It does not independently establish Medicare coverage, medical necessity, or separate payment.

Providers should determine whether the underlying procedure supports laterality and whether the payer requires RT.

This becomes particularly important when bilateral procedures are involved.

For practitioners and hospital outpatient departments, CMS states that bilateral surgical procedures generally should be reported with Modifier 50 and one unit of service on one claim line, unless the code descriptor itself defines the procedure as bilateral.

ASC reporting differs. CMS states that an ASC should report an applicable bilateral surgical procedure on two claim lines with one unit each, using LT and RT on separate lines.

Therefore, providers should not assume that RT and LT reporting is interchangeable with Modifier 50 across all settings.

Modifier RT and NCCI Edits

CMS includes RT among its NCCI PTP-associated anatomical modifiers.

These modifiers may be appropriate when procedures are performed at legitimately separate anatomical sites.

CMS notes that many NCCI edits involving paired organs or structures—such as the eyes, ears, extremities, lungs, and kidneys—have a Correct Coding Modifier Indicator of 1 because separate reporting may be appropriate when procedures are performed on contralateral structures.

A CCMI of 1 means an appropriate NCCI-associated modifier may bypass the edit when the clinical circumstances support it.

A CCMI of 0 means an NCCI-associated modifier cannot bypass the edit.

RT should never be appended solely because a claim contains an NCCI edit. The medical record must support the right-sided anatomical distinction.

Modifier RT vs. Modifier LT

Modifier RT: Identifies a procedure or service performed on the right side.

Modifier LT: Identifies a procedure or service performed on the left side.

The modifiers serve parallel purposes and allow payers to distinguish services performed on opposite sides of the body.

When separate procedures are performed on both sides, providers must still determine whether the payer expects separate RT and LT reporting or bilateral reporting with Modifier 50.

Modifier RT vs. Modifier 50

Modifier RT: Identifies the right side of the body.

Modifier 50: Identifies an eligible bilateral procedure.

RT should generally be used when the claim needs to communicate that a service was specifically performed on the right side.

Modifier 50 addresses a different circumstance: the same eligible procedure being performed bilaterally.

The correct reporting method depends on the procedure, payer, and site of service. CMS specifically distinguishes bilateral reporting requirements for practitioners and hospital outpatient departments from those applicable to ASCs.

Modifier RT vs. Eyelid Modifiers E1–E4

Modifier RT identifies the right side generally, while the E1–E4 modifiers provide more precise eyelid-specific information.

Modifier E1: Upper left eyelid.

Modifier E2: Lower left eyelid.

Modifier E3: Upper right eyelid.

Modifier E4: Lower right eyelid.

For a service involving a specific eyelid, the more anatomically precise E modifier may be required instead of RT.

CMS recognizes both RT and E1–E4 as NCCI-associated anatomical modifiers, but the appropriate modifier depends on the anatomical structure represented by the procedure.

Diagnosis Laterality and Modifier RT

When an ICD-10-CM diagnosis includes laterality, the diagnosis coding and procedure modifier should accurately reflect the same documented anatomical side.

For example, a procedure submitted with RT should not ordinarily be supported solely by documentation describing a left-sided condition.

A mismatch between the procedure modifier, diagnosis code, and medical record may lead to claim-processing problems or additional documentation review.

RT does not correct an incorrectly selected diagnosis code. Both the diagnosis and procedure reporting should accurately represent the documented service.

Common Billing Mistakes

Using the Wrong Side: Reporting RT when documentation identifies the left side creates conflicting claim information.

Using RT for Every Bilateral Procedure: Medicare may require Modifier 50 rather than separate RT and LT reporting depending on the procedure and setting.

Ignoring ASC Rules: CMS specifically permits separate RT and LT claim lines for applicable bilateral surgical procedures in the ASC setting.

Using RT on Non-Lateral Services: RT should only be reported when right-versus-left anatomy is relevant.

Using RT to Bypass NCCI: The modifier should not be appended solely to override an edit without a legitimate separate anatomical circumstance.

Diagnosis and Modifier Conflict: Reporting RT with documentation or diagnosis coding indicating only the left side can create a laterality discrepancy.

Common Denial Reasons

Incorrect Laterality: The medical record does not support the right side reported with RT.

Missing Laterality: A payer requires anatomical identification but the applicable modifier is absent.

Incorrect Bilateral Reporting: RT and LT are reported when the procedure or payer requires Modifier 50 or another reporting method.

NCCI Requirements Not Met: Documentation does not support separate anatomical reporting for services subject to an NCCI edit.

Diagnosis Conflict: Diagnosis laterality conflicts with the RT modifier.

Medical Necessity Not Supported: The underlying service fails applicable coverage or documentation requirements.

Frequently Asked Questions

Can Modifier RT and Modifier LT be reported for procedures performed on both sides?
Sometimes. The correct method depends on the procedure, payer, and setting. CMS generally requires Modifier 50 for applicable bilateral surgical procedures billed by practitioners and hospital outpatient departments, while ASCs may report separate RT and LT lines for qualifying bilateral procedures.

Can Modifier RT bypass an NCCI edit?
RT is an NCCI PTP-associated anatomical modifier, but it can only bypass an edit when the edit permits modifier use and the clinical circumstances legitimately support a separate anatomical site.