Introduction
Modifier 24 is one of the most important Evaluation and Management (E/M) modifiers used in medical billing. It allows providers to report an E/M service performed during a patient’s postoperative (global) period when the visit is completely unrelated to the original surgery. Without Modifier 24, many payers—including Medicare—consider postoperative E/M visits part of the global surgical package and may deny separate payment. Proper documentation demonstrating that the visit is unrelated is essential for reimbursement. (CMS)
Modifier Number
24
Modifier Name
Unrelated Evaluation and Management Service During a Postoperative Period
Note: The wording above is the commonly recognized modifier name. The official CPT® descriptor is maintained by the American Medical Association (AMA) and should be referenced from the licensed CPT® codebook.
Plain English Explanation
Imagine a patient has knee surgery. Two weeks later, the same physician sees the patient for newly diagnosed high blood pressure. The office visit has nothing to do with the knee surgery.
Normally, visits during the postoperative period are included in the surgery payment. However, because this visit is for a completely different medical problem, Modifier 24 tells the payer:
“This office visit is unrelated to the previous surgery. Please evaluate it separately.”
Purpose of Modifier 24
Modifier 24 informs the payer that:
- The patient is still within the global surgical period.
- The E/M service is unrelated to the surgery.
- The visit deserves separate reimbursement because it is not included in the global surgical package. (CMS)
Understanding the Global Surgical Period
Before learning Modifier 24, you must understand the Global Surgical Package.
A surgical payment usually includes:
- Preoperative services
- The surgery itself
- Routine postoperative visits
- Suture removal
- Dressing changes
- Routine follow-up care
- Management of expected recovery
Common Medicare global periods are:
| Procedure Type | Typical Global Period |
|---|---|
| Minor Procedure | 0 or 10 Days |
| Major Surgery | 90 Days |
Routine postoperative care is generally included in the surgical payment. Modifier 24 is only for visits that are not relatedto that surgery. (CMS)
When to Use Modifier 24
Use Modifier 24 when all of the following apply:
- The patient is in the postoperative global period.
- The same physician (or same specialty within the same group, as applicable under payer rules) provides an E/M service.
- The reason for the visit is completely unrelated to the original surgery.
- The documentation clearly supports that the condition is unrelated. (CMS)
Examples
✔ Migraine during postoperative period
✔ Diabetes management
✔ Hypertension follow-up
✔ Ear infection
✔ Urinary tract infection
✔ Allergic reaction unrelated to surgery
✔ New skin rash
When NOT to Use Modifier 24
Do not use Modifier 24 for:
- Routine postoperative visits
- Wound checks
- Suture removal
- Dressing changes
- Pain related to surgery
- Surgical complications that are part of postoperative care
- Infection directly related to the surgical site
- Expected follow-up after surgery (CMS)
Medicare Rules
Medicare generally allows separate payment for an E/M service during the postoperative period only when:
- The visit is unrelated to the original surgery.
- Modifier 24 is appended to the E/M code.
- Documentation supports the unrelated nature of the visit.
- The diagnosis reflects a condition unrelated to the surgical procedure. (CMS)
Medicare Will Usually Pay
- New hypertension evaluation after cataract surgery
- Diabetes follow-up after knee replacement
- Asthma exacerbation after hernia repair
Medicare Will Usually Not Pay
- Surgical wound infection evaluation
- Routine postoperative pain management
- Expected postoperative follow-up visits
Commercial Insurance Rules
Most commercial payers follow principles similar to Medicare, but policies differ.
Many commercial insurers:
- Require Modifier 24 on the E/M code.
- Require documentation supporting the unrelated diagnosis.
- May request medical records.
- May apply payer-specific global period rules.
Always verify the individual payer’s billing policy before claim submission. (BridgeSpan Health)
Documentation Requirements
Good documentation should include:
- Chief complaint
- History of present illness
- Examination findings
- Medical decision making
- Assessment
- Treatment plan
- Diagnosis unrelated to surgery
- Statement that the visit is unrelated to the postoperative care when appropriate
Poor documentation is a common reason for denials.
Real Billing Example
Scenario 1 – Correct Use
Procedure
Cataract surgery performed.
Global Period
90 days.
Two weeks later
Patient returns with severe dizziness and uncontrolled hypertension.
The physician performs:
- History
- Examination
- Medication adjustment
- Blood pressure management
Coding
- 99213-24
The visit is unrelated to the cataract surgery.
Scenario 2 – Incorrect Use
Patient returns after knee replacement because the incision is red and painful.
Provider evaluates the surgical wound.
Coding
Do not append Modifier 24 because the visit relates to postoperative care.
CMS-1500 Claim Example
| Field | Value |
|---|---|
| CPT | 99213 |
| Modifier | 24 |
| Diagnosis Pointer | Links to the unrelated diagnosis |
| Units | 1 |
| Charges | Provider’s billed amount |
Common Denial Reasons
- Missing Modifier 24
- Diagnosis related to surgery
- Insufficient documentation
- Visit considered routine postoperative care
- Modifier appended to a non-E/M code
- Global period edits by the payer
How to Correct the Denial
- Review the explanation of benefits (EOB) or electronic remittance advice (ERA).
- Verify that the visit truly addressed an unrelated condition.
- Confirm the correct diagnosis coding.
- Ensure Modifier 24 is appended to the E/M code.
- Submit supporting medical records if requested.
- Appeal when documentation supports separate reimbursement.
Coding Tips
- Append Modifier 24 only to E/M services.
- Do not use it to bypass global surgery edits.
- Use a diagnosis that clearly supports the unrelated condition.
- Maintain clear documentation explaining why the visit is unrelated.
- Review payer-specific policies before billing.
Frequently Asked Questions
Q1. Can Modifier 24 be used with surgical CPT codes?
Answer: No. It is used with appropriate E/M services, not surgical procedure codes.
Q2. Can Modifier 24 be used after every surgery?
Answer: No. It is only appropriate when the E/M visit is unrelated to the surgery.
Q3. Can I bill a wound check with Modifier 24?
Answer: No. Routine wound care and follow-up are generally included in the global surgical package.
Q4. Does Modifier 24 guarantee payment?
Answer: No. Payment depends on payer policy and whether the documentation supports the unrelated nature of the visit.
AR Caller Tips
When following up on a denied Modifier 24 claim:
- Confirm the claim included Modifier 24.
- Verify the diagnosis is unrelated to the surgery.
- Ask the payer whether additional documentation is required.
- If necessary, submit the medical records with an appeal.
- Document the call reference number and representative’s comments.
Interview Questions
Question 1
What is Modifier 24 used for?
Answer: It identifies an E/M service performed during a postoperative global period that is unrelated to the original surgical procedure.
Question 2
Can Modifier 24 be billed for postoperative complications?
Answer: Generally, no. Visits for complications related to the surgery are typically part of the global surgical package unless specific payer policies provide otherwise.
Question 3
Why is documentation important for Modifier 24?
Answer: The documentation must clearly demonstrate that the visit addressed a condition unrelated to the surgery; otherwise, the payer may deny separate reimbursement.
Practice Scenario
Scenario
A patient undergoes an appendectomy.
Twenty days later, the patient develops seasonal allergies and schedules an office visit with the same surgeon. The physician evaluates the allergy symptoms, prescribes medication, and documents that the condition is unrelated to the appendectomy.
Question
Should Modifier 24 be reported?
Answer
Yes. The patient is still within the postoperative period, but the E/M service is for a separate, unrelated medical condition. Modifier 24 may be appropriate if the documentation supports the unrelated diagnosis.
Common Billing Mistakes
- Using Modifier 24 for routine postoperative visits.
- Billing surgical-site complications with Modifier 24.
- Failing to document the unrelated condition.
- Appending Modifier 24 to procedure codes instead of E/M codes.
- Assuming all payers follow identical global surgery rules.
Related Modifiers
- Modifier 25 – Significant, separately identifiable E/M service on the same day as a procedure.
- Modifier 57 – Decision for surgery.
- Modifier 79 – Unrelated procedure or service during the postoperative period.
Key Takeaways
- Modifier 24 is used only with appropriate E/M services.
- The visit must occur during the global postoperative period.
- The medical problem must be unrelated to the original surgery.
- Documentation is critical to support separate payment.
- Verify payer-specific policies before billing.
References
- CMS Medicare Claims Processing Manual
- CMS Medicare Learning Network (MLN) – Global Surgery Booklet (CMS)
- Current payer-specific billing policies
- Licensed AMA CPT® codebook for official CPT descriptors
Conclusion
Modifier 24 is an important E/M modifier that allows providers to receive separate reimbursement for medically necessary office visits performed during a patient’s postoperative period when those visits are completely unrelated to the original surgery. Correct use requires understanding the global surgical package, assigning the modifier only to eligible E/M services, selecting appropriate diagnosis codes, and maintaining clear documentation. When used correctly, Modifier 24 helps reduce unnecessary denials, supports compliant billing, and ensures providers are reimbursed appropriately for unrelated patient care.
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 educational materials, and general medical billing practices. 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 refer to the current AMA CPT® codebook, CMS manuals, National Correct Coding Initiative (NCCI) policies, Medicare Administrative Contractor (MAC) guidance, and payer-specific billing policies before coding or submitting claims.