Direct answer: Medical billing modifiers are two-character additions to procedure codes that communicate specific circumstances about a service. They may identify a separate E/M service, professional or technical component, distinct procedure, laterality, repeat service, bilateral procedure, or service performed during a global surgical period. Every modifier must be supported by the medical record and the applicable payer’s rules.
Last reviewed: August 2026. This article provides general billing and coding information. Always confirm current codebook instructions, payer policies, and documentation requirements for the date of service.
What Are Medical Billing Modifiers?
A modifier adds information to a CPT or HCPCS procedure code without changing the basic identity of the reported service. It helps explain circumstances that may affect claim processing, coding edits, coverage, or payment.
Modifiers may communicate that:
- An E/M service was separately performed on the same day as a procedure
- A service involved only the professional or technical component
- Two procedures were separate under applicable coding rules
- A service involved the right or left side
- A procedure was bilateral
- A service was repeated
- A procedure occurred during a postoperative global period
- A service was reduced, discontinued, or unusually difficult
A modifier does not guarantee payment. The claim must still satisfy documentation, coverage, authorization, medical-necessity, enrollment, and payer requirements.
Quick Reference: Common Medical Billing Modifiers
| Modifier | Common purpose | Primary risk |
|---|---|---|
| 25 | Separately supported E/M service on the same day as another service | E/M work is not sufficiently separate from the procedure |
| 26 | Professional component | The code does not support component billing |
| TC | Technical component | Incorrect entity or setting bills the technical portion |
| 59 | Distinct non-E/M procedural service when no better modifier applies | Used only to override an edit |
| XE, XP, XS, XU | More specific circumstances previously reported with modifier 59 | Documentation does not support the selected distinction |
| RT and LT | Right or left side | Laterality conflicts with documentation or diagnosis |
| 50 | Bilateral procedure | Payer requires different bilateral reporting |
| 24 | Unrelated E/M service during a postoperative period | Visit is related to routine postoperative care |
| 57 | E/M service resulting in the decision for major surgery | Used for a minor procedure or unsupported decision |
| 58, 78, 79 | Procedures performed during a postoperative period | Wrong relationship to the original procedure |
| 76 and 77 | Repeat procedures | Duplicate billing or incorrect performing professional |
| 91 | Eligible repeat clinical diagnostic laboratory test | Used for confirmation, equipment issues, or an unneeded repeat |
| 52 and 53 | Reduced or discontinued service | Documentation does not explain what occurred |
| 22 | Substantially increased procedural work | Insufficient documentation of the additional work |
Modifier 25: Separate E/M Service on the Same Day
Modifier 25 may be appended to an eligible E/M code when the provider performs a medically necessary E/M service that is significant and separately identifiable from another procedure or service performed on the same date.
The E/M service does not necessarily require a separate diagnosis. However, the documentation should demonstrate work beyond the evaluation normally associated with the other service.
Documentation should establish:
- The patient’s complaint or condition requiring evaluation
- The medically necessary history, examination, and decision-making or time
- The separately performed E/M work
- The procedure or other service provided on the same date
Do not append modifier 25 automatically whenever an office visit and procedure appear on the same claim. Routine pre-service and post-service work included in the procedure generally does not justify separate E/M reporting.
Modifiers 26 and TC: Professional and Technical Components
Some diagnostic services can be divided into professional and technical components.
- Modifier 26 generally identifies the professional component, such as an eligible physician interpretation.
- Modifier TC generally identifies the technical component, such as eligible equipment, supplies, and technical personnel.
If the same eligible entity provides and bills the complete service, the service may be reported globally without either component modifier, subject to payer and setting rules.
Not every procedure code can be divided into components. Check the applicable fee-schedule indicator, codebook instructions, payer policy, provider arrangement, and service location before using modifier 26 or TC.
Modifier 59: Distinct Procedural Service
Modifier 59 is associated with distinct non-E/M procedural services that would not normally be reported together but may be separately reportable under supported circumstances.
CMS advises using modifier 59 only when no more descriptive modifier explains the relationship between the procedures. Documentation may need to demonstrate a separate encounter, separate anatomic site, separate lesion, separate incision, or another recognized distinction.
Modifier 59 should not be:
- Added only because a claim edit caused a denial
- Used without reviewing the applicable NCCI edit
- Appended to an E/M service
- Used when a more specific modifier accurately describes the service
- Reported when the documentation does not support separate services
Modifiers XE, XP, XS, and XU
These modifiers provide greater specificity for circumstances that might otherwise be reported with modifier 59:
- XE: The service was distinct because it occurred during a separate encounter.
- XP: The service was distinct because it was performed by a different practitioner.
- XS: The service was distinct because it involved a separate organ or structure.
- XU: The service was distinct because it did not overlap the usual components of the primary service.
Use the modifier that most accurately describes the documented situation and is accepted by the payer. Do not use an X modifier solely to force payment of a bundled service.
RT, LT, and Modifier 50: Laterality and Bilateral Services
RT and LT communicate that an eligible service involved the right or left side. Modifier 50 may be used for an eligible bilateral procedure.
Before billing, verify:
- The procedure code supports laterality or bilateral reporting
- The medical record identifies the correct side
- The diagnosis laterality is consistent
- The payer’s bilateral billing method
- The correct number of claim lines and units
Payer instructions can differ. Some payers expect modifier 50 on one line, while others may require RT and LT on separate lines or another reporting method.
Modifier 51: Multiple Procedures
Modifier 51 may communicate that multiple eligible procedures were performed during the same operative session. Payers may apply multiple-procedure payment rules when appropriate.
Do not assume every additional code requires modifier 51. Some codes are exempt, some services are bundled, and some payers identify and rank multiple procedures through their claim-processing systems.
Modifier 24: Unrelated E/M During a Postoperative Period
Modifier 24 may be used with an eligible E/M service performed during a postoperative global period when the visit is unrelated to the original procedure.
The medical record should clearly explain:
- The reason for the new visit
- Why the condition is unrelated to routine postoperative care
- The evaluation and management performed
- The relationship, or lack of relationship, to the original procedure
Routine recovery care and management of expected postoperative issues generally remain subject to the global surgical package.
Modifier 57: Decision for Surgery
Modifier 57 may apply when an E/M service results in the initial decision to perform a major surgery. It is associated with the global-surgery rules applicable to major procedures.
It should not be used automatically for an E/M service performed before every procedure. Confirm the procedure’s global indicator, the timing of the decision, payer policy, and documentation.
Modifiers 58, 78, and 79 During the Global Period
These modifiers describe different relationships between a subsequent procedure and an earlier surgery:
- Modifier 58: May apply to a staged, planned, more extensive, or therapy-related procedure during the postoperative period.
- Modifier 78: May apply to an unplanned return to an operating or procedure room for a related procedure during the postoperative period.
- Modifier 79: May apply to an unrelated procedure performed during the postoperative period.
Selecting among them requires careful review of the clinical relationship, timing, care setting, global-surgery rules, and documentation.
Modifiers 76 and 77: Repeat Procedures
Modifier 76 may identify an eligible repeat procedure or service performed by the same physician or other qualified healthcare professional. Modifier 77 may apply when another physician or qualified professional performs the repeat service.
The documentation should explain why the repetition was medically necessary. Confirm that the second service is a true repeat rather than a duplicate submission or correction of the original claim.
Modifier 91: Repeat Laboratory Test
Modifier 91 may apply when an eligible clinical diagnostic laboratory test is repeated on the same date to obtain medically necessary subsequent results.
It should not be used simply because:
- The original result is being confirmed unnecessarily
- A specimen or equipment problem required the test to be rerun
- The claim was accidentally submitted twice
- A panel code should have been reported instead
Review the laboratory documentation, panel rules, units, NCCI edits, and payer requirements.
Modifiers 52 and 53: Reduced or Discontinued Services
Modifier 52 may apply when an eligible service is intentionally reduced under circumstances allowed by the code and payer. Modifier 53 may apply when a procedure is started but discontinued because continuing it would place the patient at risk or because of another qualifying circumstance.
The operative or procedure note should explain what was planned, what was completed, why the service was reduced or discontinued, and the patient’s condition.
Modifier 22: Increased Procedural Services
Modifier 22 may be considered when the work required for a procedure is substantially greater than typically required.
Documentation should identify the specific circumstances and additional work, such as increased intensity, time, technical difficulty, or complexity. A brief statement that the case was “difficult” is generally insufficient.
Submit the supporting documentation according to the payer’s process. Additional payment is not guaranteed.
Telehealth Modifiers 95 and 93
Modifier 95 is commonly associated with eligible synchronous telemedicine services. Modifier 93 may be used for eligible synchronous audio-only services under applicable rules.
Telehealth requirements can vary by payer, plan, provider type, service, patient location, date of service, and place-of-service code. Confirm the current policy before submitting the claim.
Medicare Liability Modifiers
Certain HCPCS modifiers communicate Medicare beneficiary-notice and coverage circumstances. Examples include GA, GX, GY, and GZ.
These modifiers have different meanings and should not be treated as interchangeable. Their correct use depends on whether a service is expected to be denied, whether a required or voluntary notice was issued, and whether the item or service is excluded from Medicare coverage.
Follow current Medicare Administrative Contractor guidance and the organization’s compliant Advance Beneficiary Notice process.
Common Modifier Billing Errors
- Using modifier 25 for routine work included in a procedure
- Using modifier 59 or an X modifier only to bypass an edit
- Reporting modifier 26 or TC on a code that cannot be split
- Submitting RT or LT when the documentation identifies the opposite side
- Using modifier 50 when the payer requires separate RT and LT lines
- Confusing modifiers 58, 78, and 79 during a global period
- Using modifier 91 for a laboratory rerun caused by an error
- Reporting modifier 22 without detailed supporting documentation
- Assuming all payers process modifiers identically
- Failing to update billing-system edits when policies change
A Safe Modifier Review Process
- Identify the service documented by the provider.
- Confirm the correct procedure code for the date of service.
- Determine whether a modifier is necessary.
- Review the official codebook instructions.
- Check applicable NCCI edits and modifier indicators.
- Review payer and Medicare Administrative Contractor policies.
- Confirm that the medical record supports the modifier.
- Check modifier order when multiple modifiers are required.
- Scrub the claim before submission.
- Analyze modifier-related denials for recurring problems.
How Modifier Errors Affect Revenue
An incorrect modifier can result in a rejection, denial, reduced payment, overpayment, medical-record request, or compliance review. Automatically adding modifiers to increase reimbursement creates unnecessary risk.
Practices should monitor modifier usage by provider, location, procedure, payer, denial reason, and payment outcome. Unusual patterns should be reviewed before they become recurring claim problems.
When Medical Billing Support Can Help
Modifier selection becomes more difficult when a practice handles multiple specialties, surgical global periods, diagnostic components, payer-specific edits, and complex documentation.
An experienced billing team can help review claim edits, identify modifier-related denials, monitor payer policies, provide documentation feedback, and establish consistent coding workflows.
Learn more about our medical billing and coding services and our approach to accounts receivable follow-up.
Frequently Asked Questions
What is the most commonly misunderstood medical billing modifier?
Modifier 59 is frequently misunderstood because it should not be used merely to override a coding edit. The documented circumstances must support a distinct service, and a more descriptive modifier should be used when available.
Can modifier 25 and modifier 59 be used interchangeably?
No. Modifier 25 applies to an eligible, separately supported E/M service performed on the same date as another service. Modifier 59 applies to eligible distinct non-E/M procedural services.
Can a claim contain more than one modifier?
Yes, when multiple modifiers are necessary and supported. Modifier order and claim-line reporting should follow the applicable payer’s instructions.
Does adding a modifier guarantee payment?
No. The claim must still meet coding, documentation, coverage, medical-necessity, authorization, enrollment, and payer requirements.
Do Medicare, Medicaid, and commercial payers use modifiers the same way?
Not always. They may recognize different modifiers or apply different reporting and payment rules. Verify the policy for the patient’s payer and date of service.
