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Modifier 77 is used to report a repeat procedure or service performed by another physician or other qualified health care professional on the same date of service. It informs the payer that the repeated procedure was medically necessary and was performed by a different physician, not as a duplicate billing error.

Modifier 77 is frequently used in emergency medicine, radiology, cardiology, surgery, and hospital settings where a patient’s condition changes and another physician must repeat the same procedure for further evaluation or treatment. CMS recognizes Modifier 77 as the correct modifier for repeat procedures performed by another physician or qualified health care professional.

Modifier Number

77

Modifier Name

Repeat Procedure by Another Physician or Other Qualified Health Care Professional

Note: The official CPT® descriptor is maintained by the American Medical Association (AMA). Always refer to the current licensed CPT® codebook for the official wording.

Plain English Explanation

Modifier 77 tells the payer:

“The same procedure had to be repeated on the same day by a different physician because it was medically necessary. This is not a duplicate claim.”

Purpose of Modifier 77

Modifier 77 is used to:

  • Identify medically necessary repeat procedures.
  • Distinguish repeat services from duplicate billing.
  • Indicate that another physician performed the repeated procedure.
  • Support appropriate reimbursement.
  • Comply with Medicare and commercial payer billing guidelines.

Understanding Modifier 77

Modifier 77 applies when:

  • The same CPT® code is repeated.
  • The repeat service is performed by another physician or qualified healthcare professional.
  • The repeat procedure is medically necessary.
  • The repeat occurs after the original procedure on the same date of service.

The repeated procedure should generally be billed on a separate claim line with Modifier 77.

When to Use Modifier 77

Modifier 77 is appropriate when:

  • A different physician repeats the same procedure.
  • The patient’s condition changes and requires another evaluation.
  • The repeat procedure is medically necessary.
  • Documentation supports the repeat service.

Common Examples

✔ Repeat EKG interpreted by another cardiologist.

✔ Repeat chest X-ray interpreted by another radiologist.

✔ Repeat ultrasound by another physician because of clinical deterioration.

✔ Repeat endoscopy performed by another gastroenterologist.

✔ Repeat CT scan interpreted by another physician after trauma progression.

When NOT to Use Modifier 77

Do not use Modifier 77 when:

  • The same physician repeats the procedure (use Modifier 76).
  • The repeated service is a laboratory test (Modifier 91 may apply).
  • The repeat is due to equipment malfunction or poor image quality.
  • The procedure is repeated because of specimen handling errors.
  • The second claim is simply a duplicate submission.

Medicare Rules

Important Medicare guidance includes:

  • Modifier 77 identifies a repeat procedure performed by another physician or qualified healthcare professional.
  • The repeated procedure must be medically necessary.
  • The repeated procedure should be reported on a separate claim line.
  • Documentation must clearly explain why the repeat service was required.
  • Physicians in the same group and same specialty may, under Medicare rules, be considered the “same physician,” in which case Modifier 76—not Modifier 77—may be appropriate.

Commercial Insurance Rules

Most commercial insurers:

  • Recognize Modifier 77.
  • Apply duplicate claim edits.
  • Require documentation explaining medical necessity.
  • May request medical records before payment.
  • Generally follow CMS guidance with payer-specific variations.

Always verify the payer’s billing policy before claim submission.

Documentation Requirements

Documentation should include:

  • Initial procedure.
  • Repeat procedure.
  • Medical necessity.
  • Time of each procedure.
  • Name of the first physician.
  • Name of the second physician.
  • Physician documentation.
  • Interpretation/report when applicable.

Documentation should clearly explain why another physician performed the repeat service.

Real Billing Examples

Example 1 – Repeat EKG

A patient presents to the Emergency Department with chest pain.

  • 10:00 AM: Dr. Smith performs and interprets an EKG.
  • 1:30 PM: The patient’s condition worsens, and Dr. Jones repeats and interprets another EKG.

Billing

Dr. Smith

  • 93010-26

Dr. Jones

  • 93010-26-77

This identifies the second interpretation as a medically necessary repeat procedure by another physician.

Example 2 – Repeat Chest X-ray

A trauma patient undergoes an initial chest X-ray interpreted by the emergency physician.

Later that day, a radiologist repeats and interprets another chest X-ray because of worsening respiratory status.

Modifier 77 is appropriate.

Example 3 – Repeat Ultrasound

An obstetrician performs a fetal ultrasound in the morning.

Later the same day, a maternal-fetal medicine specialist repeats the ultrasound because of acute fetal distress.

Modifier 77 may be appropriate when documentation supports medical necessity.

Example 4 – Incorrect Use

The same cardiologist repeats an EKG later the same day.

Modifier 77 should not be used.

Modifier 76 is appropriate because the same physician repeated the procedure.

CMS-1500 Claim Example

FieldExample
CPT Code93010
Modifier77 (repeat service only)
Diagnosis PointerAppropriate ICD-10-CM diagnosis
Units1
ChargesProvider’s billed amount

Billing Example

LineCPT® Code
Physician A93010-26
Physician B93010-26-77

Common Denial Reasons

  • Duplicate billing.
  • No documentation supporting medical necessity.
  • Wrong modifier (76 instead of 77).
  • Repeat due to technical failure.
  • Physicians belong to the same group and specialty where Medicare considers them the same physician.
  • Modifier omitted from the repeated service.

How to Correct the Denial

  1. Review the Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA).
  2. Verify that another physician performed the repeated procedure.
  3. Confirm medical necessity.
  4. Submit physician documentation and interpretation reports.
  5. Ensure Modifier 77 was appended only to the repeated procedure.
  6. Appeal with supporting medical records if appropriate.

Coding Tips

  • Verify that another physician performed the repeated procedure.
  • Report the repeated procedure on a separate claim line.
  • Do not report Modifier 77 on Evaluation & Management (E/M) services.
  • Do not use Modifier 77 for repeat laboratory tests.
  • Review Medicare group practice rules before selecting Modifier 76 or 77.

Modifier 77 vs Modifier 76 vs Modifier 91

ModifierPurpose
76Repeat procedure by the same physician.
77Repeat procedure by another physician.
91Repeat clinical diagnostic laboratory test.

Modifier 77 vs Modifier 59

ModifierPurpose
77Same procedure repeated by another physician because of medical necessity.
59Distinct procedural service; not intended for repeat procedures.

Modifier 77 vs Modifier XP

ModifierPurpose
77Repeat of the same procedure by another physician.
XPDistinct service because it was performed by a separate practitioner, typically used to identify a distinct procedural service rather than a repeat procedure.

Frequently Asked Questions (FAQs)

Q1. What is Modifier 77 used for?

Answer: Modifier 77 identifies a medically necessary repeat procedure performed by another physician or qualified healthcare professional on the same date of service.

Q2. What is the difference between Modifier 76 and Modifier 77?

Answer: Modifier 76 is used when the same physician repeats the procedure. Modifier 77 is used when another physician repeats the same medically necessary procedure.

Q3. Can Modifier 77 be used for laboratory testing?

Answer: No. Repeat clinical diagnostic laboratory tests are generally reported with Modifier 91.

Q4. Can Modifier 77 be appended to E/M services?

Answer: No. Modifier 77 is intended for repeat procedures or services and should not be appended to Evaluation & Management services.

AR Caller Tips

When following up on a denied Modifier 77 claim:

  • Verify another physician performed the repeated procedure.
  • Confirm documentation supports medical necessity.
  • Ensure the repeated service was billed on a separate claim line.
  • Submit physician notes and interpretation reports if requested.
  • Record the payer representative’s name, reference number, and follow-up instructions.

Interview Questions

Question 1

What is Modifier 77?

Answer: It identifies a medically necessary repeat procedure performed by another physician or qualified healthcare professional.

Question 2

What is the difference between Modifier 76 and Modifier 77?

Answer: Modifier 76 is for the same physician. Modifier 77 is for another physician.

Question 3

When should Modifier 91 be used instead of Modifier 77?

Answer: Modifier 91 is used for repeat clinical diagnostic laboratory tests rather than repeat procedures.

Practice Scenario

Scenario

A patient arrives in the Emergency Department with chest pain.

An emergency physician performs and interprets an EKG at 9:00 AM. Several hours later, the patient’s symptoms worsen, and a consulting cardiologist performs and interprets another EKG.

Question

Should Modifier 77 be reported?

Answer

Yes. Because the same procedure was repeated by another physician due to medical necessity, the cardiologist’s interpretation should be reported with Modifier 77.

Related Modifiers

  • Modifier 76 – Repeat Procedure by Same Physician
  • Modifier 91 – Repeat Clinical Diagnostic Laboratory Test
  • Modifier 59 – Distinct Procedural Service
  • Modifier XP – Separate Practitioner

Common Billing Mistakes

  • Using Modifier 77 when the same physician repeated the procedure.
  • Using Modifier 77 for laboratory testing.
  • Reporting duplicate claims without documentation.
  • Billing multiple units instead of separate claim lines.
  • Using Modifier 77 on E/M services.

Key Takeaways

  • Modifier 77 reports a repeat procedure performed by another physician.
  • The repeated procedure must be medically necessary.
  • Bill the repeated procedure on a separate claim line.
  • Do not use Modifier 77 for laboratory tests or E/M services.
  • Proper documentation prevents duplicate claim denials and supports compliant reimbursement.

References

  • CMS Medicare Coverage Database – Billing and Coding: Repeat or Duplicate Services on the Same Day.
  • CMS Medicare Coverage Database – Repeat X-ray or EKG Interpretations by Same or Different Physician.
  • Noridian Medicare – Modifier 77 Guidance (updated May 2025).
  • AMA CPT® Professional Edition (licensed codebook).

Conclusion

Modifier 77 is an essential modifier for reporting medically necessary repeat procedures performed by another physician or qualified healthcare professional. Correct application helps distinguish legitimate repeat services from duplicate billing, supports accurate reimbursement, and reduces denials. Success with Modifier 77 depends on clear documentation, proper claim-line reporting, and compliance with CMS and payer-specific billing guidelines.

Educational Disclaimer

This article was prepared with the assistance of artificial intelligence (AI) for educational and informational purposes. It is based on publicly available CMS guidance, Medicare billing resources, and general medical billing principles. It is not an official publication of the American Medical Association (AMA), CMS, or any insurance payer. CPT® is a registered trademark of the American Medical Association. Always consult the latest AMA CPT® codebook, CMS manuals, Medicare Administrative Contractor (MAC) guidance, National Correct Coding Initiative (NCCI) policies, and payer-specific billing policies before coding, billing, or submitting claims.