Medical billing uses special codes called modifiers that give extra information about services provided to patients. These modifiers are two-digit numbers added to procedure codes to explain special situations. Modifier 79 is one of the most commonly used modifiers in medical billing. Understanding when and how to use it correctly helps healthcare providers get paid properly and avoid claim denials.
Modifier 79 tells insurance companies that a procedure performed during the post-operative period was unrelated to the original surgery. This matters because insurance has specific rules about what they will pay during recovery time after surgery. Without the right modifier, claims get denied and providers lose money they should receive. Getting modifier 79 usage right is important for any medical practice that performs surgeries or procedures.
What Modifier 79 Means
Modifier 79 has an official description that says “Unrelated Procedure or Service by the Same Physician During the Postoperative Period.” This long description contains several important parts that explain exactly what the modifier does.
Breaking Down Each Part
The first part says “unrelated procedure or service.” This means the new procedure has nothing to do with the original surgery. It is for a completely different medical problem in a different body area or for a different reason. The two procedures are separate and independent from each other.
For example, if a patient had knee surgery and later needs gallbladder surgery, these are unrelated. The gallbladder has nothing to do with the knee. They are different body parts with different medical problems.
The second part says “by the same physician.” The same doctor who did the original surgery is now doing the new procedure. This is very important. If a different doctor does the new procedure, modifier 79 is not needed. The modifier only applies when one doctor performs both procedures.
The third part says “during the postoperative period.” Every surgery has a global period. A global period is a set number of days after surgery when follow-up care is included in the original surgery payment. Common global periods are zero days, ten days, or ninety days
depending on the procedure. Modifier 79 is used when the new procedure happens within this global period.
Why Insurance Companies Need This Information
Insurance companies pay surgeons a single fee that covers the surgery plus all normal follow-up care during the global period. This follow-up care includes office visits to check healing, removing stitches, changing bandages, and treating normal problems after surgery. The surgeon cannot bill separately for these follow-up services because they are already paid for in the original surgery fee.
But what happens if the patient needs a completely different procedure during this time? The surgeon should get paid for this new procedure even though the patient is still in the recovery period from the first surgery. Modifier 79 tells the insurance company “this new procedure is unrelated to the original surgery, so please pay for it separately.”
Without this modifier, the insurance company might deny the claim. They might think it is just follow-up care from the first surgery that should not be billed separately. The modifier prevents this confusion and denial.
The Simple Rule
The basic rule for modifier 79 is simple:
- Same doctor who did the first surgery
- Performs a new procedure
- During the recovery period of the first surgery
- New procedure is unrelated to the first surgery
- Add modifier 79 to the new procedure code
When all these conditions are true, use modifier 79. If any condition is not true, do not use it.
Understanding Global Periods
To use modifier 79 correctly, you must understand global periods. Global periods are time frames during which follow-up care after surgery is included in the surgery payment.
What Gets Included in Global Periods
When a surgeon performs a procedure, the payment covers more than just the surgery itself. The global period payment includes:
- Pre-operative work like seeing the patient the day before surgery
- The surgery itself on the day of the procedure
- All follow-up visits after surgery
- Checking how the patient is healing
- Removing sutures or staples
- Changing dressings and bandages
- Managing normal problems after surgery
The surgeon cannot bill separately for these services during the global period. They are bundled into the single surgery payment. This bundling is why modifier 79 becomes necessary when unrelated procedures happen during this time.
Different Lengths of Global Periods
Medicare and most insurance companies assign global periods to surgical procedures based on how much follow-up care the surgery typically requires. There are several standard global period lengths.
Zero-Day Global Periods
Zero-day global periods apply to minor procedures and some diagnostic tests. The payment covers only the day of the procedure with no follow-up period. Examples include simple biopsies or basic diagnostic procedures.
Ten-Day Global Periods
Ten-day global periods apply to minor surgeries. The payment covers the day of surgery plus the next ten days. Examples include minor skin lesion removals or simple wound repairs.
Ninety-Day Global Periods
Ninety-day global periods apply to major surgeries. The payment covers the day of surgery plus the next ninety days. Examples include joint replacements, gallbladder removal, or hernia repairs.
No Global Period
Some procedures have no global period. This means each service is billed separately with no bundled follow-up care.
How to Find Global Period Information
The global period for each procedure is listed in coding resources and fee schedules. Medicare publishes global period information in their physician fee schedule database. Most insurance companies follow Medicare’s global period assignments.
When you look up a procedure code, the global period information tells you how many days are included. For example, if a procedure code has a 90-day global period and was performed on
January 15, the global period runs through April 14. Any unrelated procedures by the same surgeon during that time would need modifier 79.
| Global Period | Length | What It Covers | Common Examples |
| 000 | Day of procedure only | Procedure itself, no follow-up | Simple biopsies, injections |
| 010 | Day of procedure plus 10 days | Minor follow-up care | Small skin lesion removal, simple repairs |
| 090 | Day of procedure plus 90 days | Full follow-up care | Major surgeries, joint replacements |
| MMM | No global period | Each service billed separately | Some diagnostic tests |
| XXX | Global concept does not apply | Billed per service | Certain special procedures |
When to Use Modifier 79
Modifier 79 should be used in specific situations where all the conditions for its use are met. Understanding these situations helps you apply the modifier correctly.
Same Surgeon Performing Unrelated Procedure
The main situation requiring modifier 79 is when the surgeon who performed the original procedure performs a completely different, unrelated procedure on the same patient during the original procedure’s global period. The key word is “unrelated.” The new procedure must address a different medical problem.
Here is an example: A surgeon performs gallbladder removal on a patient. Three weeks later, the same patient develops a hernia that needs surgical repair. The same surgeon performs the hernia repair. The hernia has nothing to do with the gallbladder surgery. These are unrelated procedures. Since the hernia repair happens during the 90-day global period of the gallbladder surgery, modifier 79 gets added to the hernia repair procedure code.
Different Body Area or System
Procedures on different body parts or different body systems are typically unrelated and qualify for modifier 79:
- Knee surgery followed by shoulder surgery
- Heart procedure followed by intestinal surgery
- Eye surgery followed by foot surgery
- Brain surgery followed by hand surgery
The physical separation and different medical conditions being treated make them unrelated. However, procedures on nearby areas might still be related if they address the same underlying problem. Just being in different spots does not automatically make procedures unrelated. The medical reason for the procedures matters.
Different Diagnosis Codes
When the new procedure treats a completely different diagnosis than the original surgery, this supports using modifier 79. The diagnosis codes on the two procedures should be different, showing they address separate medical problems.
Example: A patient has surgery for a broken leg. During recovery, they develop kidney stones requiring surgical removal. The broken leg diagnosis and kidney stone diagnosis are completely different. This difference in diagnoses helps show the procedures are unrelated.
Emergency or Urgent Situations
Sometimes unrelated procedures become necessary urgently during another procedure’s global period. A patient recovering from planned surgery develops an emergency requiring a different surgery. These emergency procedures clearly are unrelated to the original planned surgery and need modifier 79.
Example: A patient had elective back surgery two weeks ago. They develop acute appendicitis requiring emergency appendectomy. The back surgery and appendix surgery are obviously unrelated. Modifier 79 tells insurance the appendectomy should be paid even though it happens during the back surgery global period.
When NOT to Use Modifier 79
Understanding when not to use modifier 79 is just as important as knowing when to use it. Using it incorrectly can cause claim denials or billing problems.
Procedures Related to Original Surgery
Do not use modifier 79 for any procedure related to the original surgery. Related procedures include:
- Treating complications from the original surgery
- Re-operating on the same area because of problems
- Additional procedures needed because the first surgery did not fully fix the problem
- Procedures that are normal follow-up care
Example: A patient has knee replacement surgery. Two weeks later, the surgical site develops an infection requiring a procedure to drain the infection. This infection drainage procedure is directly related to the knee surgery. It is a complication of the knee surgery. Do not use modifier 79. This procedure should not be billed separately at all because it is included in the global period.
Normal Post-Operative Care
These services are normal post-operative care included in the global period and cannot be billed separately even with modifier 79:
- Routine follow-up visits
- Wound checks
- Suture removal
- Cast changes
- Physical therapy related to the surgery
- Managing expected recovery after surgery
Example: A surgeon sees a patient one week after surgery to check the incision and remove stitches. This is normal post-operative care. It gets no separate bill and no modifier 79. It is part of what the original surgery payment covered.
Different Surgeon Performing Procedure
If a different surgeon performs the new procedure, modifier 79 is not needed. The global period only prevents the same surgeon from billing for follow-up care. Different doctors can bill their own procedures without modifiers explaining the global period situation.
Example: Dr. Smith performs gallbladder surgery on a patient. During recovery, the patient needs hernia repair performed by Dr. Jones. Dr. Jones bills the hernia repair normally without modifier 79 because Dr. Jones did not do the original gallbladder surgery. The global period restriction does not apply to Dr. Jones.
Staged or Planned Multiple Procedures
Some treatments involve multiple procedures planned from the beginning as stages of one treatment plan. These are not unrelated procedures even if they happen weeks apart. Modifier 79 should not be used for planned stages of the same treatment.
Example: A patient needs difficult facial reconstruction requiring three separate surgeries done one month apart. All three surgeries are part of one treatment plan for the same problem. Even though they are separate procedures weeks apart, they are related to each other. Do not use modifier 79 on the second and third surgeries.
| Situation | Use Modifier 79? | Why or Why Not |
| Same doctor, unrelated procedure, during global period | YES | Meets all conditions for modifier 79 |
| Different doctor, any procedure, during global period | NO | Modifier only applies when same doctor |
| Same doctor, related procedure, during global period | NO | Use modifier 78 instead for related procedures |
| Same doctor, planned staged procedure, during global period | NO | Use modifier 58 instead for staged procedures |
| Same doctor, normal follow-up care, during global period | NO | Normal follow-up cannot be billed separately |
| Same doctor, unrelated procedure, after global period ends | NO | No modifier needed after global period |
Modifier 79 vs Modifier 78
Modifier 78 is similar to modifier 79 but used in different situations. Understanding the difference between these two modifiers prevents confusion and wrong coding.
What Modifier 78 Means
Modifier 78 is described as “Unplanned Return to the Operating Room by the Same Physician Following Initial Procedure for a Related Procedure During the Postoperative Period.” The key difference from modifier 79 is the word “related.” Modifier 78 is for related procedures, while modifier 79 is for unrelated procedures.
Modifier 78 gets used when the patient needs to go back to surgery during the global period to address problems or complications related to the original surgery. The new surgery is dealing with the same medical issue or problems caused by the first surgery.
Examples Showing the Difference
Here are examples showing when to use modifier 78 versus modifier 79:
Modifier 78 Example (Related Procedure)
A patient has colon surgery. Five days later, internal bleeding occurs requiring the patient to return to the operating room for surgery to stop the bleeding. This bleeding is a complication of the original colon surgery. It is related to the first surgery. Use modifier 78, not modifier 79.
Modifier 79 Example (Unrelated Procedure)
A patient has colon surgery. Three weeks later, the patient falls and breaks their arm requiring surgery to fix the broken bone. The broken arm has nothing to do with the colon surgery. It is an unrelated injury needing unrelated surgery. Use modifier 79, not modifier 78.
Payment Differences
Insurance companies handle payment differently for modifiers 78 and 79:
With Modifier 78:
- Insurance pays for the surgical portion of the related return surgery
- Insurance does not pay for post-operative care because that is still covered under the original surgery’s global period
- The payment is typically reduced to cover only the surgical work, not the full global payment
With Modifier 79:
- Insurance pays the full global payment for the unrelated procedure
- This includes both the surgery and its own post-operative period
- The new procedure starts its own separate global period
Understanding this payment difference helps explain why correct modifier choice matters. Using the wrong modifier affects how much the provider gets paid.
| Modifier | When to Use | Procedure Relationship | What Insurance Pays |
| 78 | Return to surgery during global period | Related to original surgery (complication or problem) | Surgery portion only, reduced payment |
| 79 | New procedure during global period | Unrelated to original surgery (different problem) | Full global payment for new procedure |
Modifier 79 vs Modifier 58
Modifier 58 is another modifier used during global periods that can be confused with modifier 79. Knowing the difference helps you choose correctly.
What Modifier 58 Means
Modifier 58 is described as “Staged or Related Procedure or Service by the Same Physician During the Postoperative Period.” This modifier is used for:
- Procedures that are planned in advance as part of the treatment plan
- Procedures that are more extensive than the original procedure for the same condition
- Procedures needed to treat the original condition after the initial procedure
Modifier 58 indicates the procedures are related to each other even though they are separate procedures done at different times. They are all part of treating the same medical problem.
Examples Showing the Difference
Modifier 58 Example (Staged or Related Procedure)
A patient has a bad tumor requiring surgical removal. The surgery plan from the beginning includes:
- First surgery: Remove the tumor
- Second surgery three weeks later: Reconstructive surgery
- Third surgery one month after that: Minor surgery to finalize the reconstruction
All three surgeries are part of one treatment plan for the same problem. Use modifier 58 on the second and third surgeries, not modifier 79.
Modifier 79 Example (Unrelated Procedure)
A patient has tumor removal surgery. During recovery, the patient develops an unrelated infection in a completely different body part requiring surgery. The infection surgery is not part of the tumor treatment plan. It is unrelated. Use modifier 79, not modifier 58.
Diagnostic Followed by Therapeutic Procedure
A common use of modifier 58 is when a diagnostic procedure is done first, then a therapeutic procedure follows during the global period to treat what was found. The diagnostic and therapeutic procedures are related because the second one treats what the first one found.
Example: A surgeon performs a diagnostic colonoscopy that finds a polyp. One week later, during the colonoscopy’s global period, the surgeon performs surgery to remove the polyp. The polyp removal is directly related to what the colonoscopy found. Use modifier 58, not modifier 79.
| Modifier | Procedure Timing | Procedure Relationship | Planning Status |
| 58 | During global period | Related or staged (same medical problem) | Often planned in advance |
| 79 | During global period | Unrelated (different medical problem) | Usually not planned with original procedure |
How to Apply Modifier 79
Knowing how to correctly add modifier 79 to claims requires understanding the mechanics of claim submission and modifier placement.
Adding the Modifier to Procedure Codes
Modifiers get added to CPT procedure codes when billing. CPT codes are five-digit codes that describe medical procedures. Modifiers are two-digit codes added after the CPT code with a hyphen.
Example:
The CPT code 44950 represents appendectomy, which is removal of the appendix. If this appendectomy is performed during the global period of an unrelated previous surgery by the same surgeon, you would bill it as:
44950-79
The -79 tells the insurance company this procedure is unrelated to the earlier surgery.
Where to Put the Modifier on Claims
Electronic Claims: When filing claims electronically, the modifier goes in the designated modifier field for that procedure line. The billing software has specific boxes or fields where modifiers are entered.
Paper Claims: When filing paper claims on the CMS-1500 form, the modifier is written in the modifier box next to the procedure code. There are usually four small boxes for modifiers next to each procedure code.
Using Multiple Modifiers Together
Sometimes a procedure code needs more than one modifier to fully describe the situation. Modifier 79 can be combined with other modifiers when necessary.
Example:
A procedure done on the right side during the global period of an unrelated surgery might be coded as:
12345-79-RT
Where:
- -79 indicates unrelated procedure during global period
- -RT indicates right side
A general rule is to put modifiers affecting payment first, followed by informational modifiers. Modifier 79 affects payment because it tells insurance to pay for a procedure during a global period, so it typically goes first when combined with other modifiers.
Documentation You Need in Medical Records
Using modifier 79 requires proper documentation in the medical record. The documentation should clearly show:
- The new procedure addresses a different medical problem than the original surgery
- The diagnosis for the new procedure is different from the original surgery diagnosis
- The medical necessity for the new procedure is clearly explained
- The new procedure is not related to complications or normal follow-up care from the original surgery
Good documentation protects against claim denials and audits. If an insurance company questions why modifier 79 was used, the medical record should make it obvious that the procedures were unrelated.
Linking Diagnosis Codes Correctly
On insurance claims, each procedure code gets linked to one or more diagnosis codes that explain why the procedure was medically necessary. When using modifier 79, make sure the new procedure is linked to diagnosis codes that are clearly different from the original surgery’s diagnosis codes.
Example:
- Original surgery: Gallbladder removal (diagnosis: gallstones)
- New surgery during global period: Hernia repair (diagnosis: inguinal hernia)
The diagnosis codes are completely different. This supports your use of modifier 79 by showing the procedures address different medical problems. If the diagnosis codes are the same or very similar, the insurance company might question whether the procedures are really unrelated.
Common Real-World Examples by Medical Specialty
Looking at real examples from different medical specialties helps understand when and how to use modifier 79 correctly.
General Surgery Examples
Example 1: Gallbladder Then Hernia
- Patient has laparoscopic cholecystectomy (gallbladder removal) on June 1st
- This procedure has a 90-day global period running through August 29th
- On July 15th, the same patient develops a hernia
- Same surgeon performs inguinal hernia repair
- The hernia is unrelated to the gallbladder surgery
- The hernia repair procedure code gets modifier 79 added
Example 2: Hemorrhoid Then Carpal Tunnel
- Patient has hemorrhoidectomy (surgical removal of hemorrhoids) on March 10th
- This has a 90-day global period
- On April 20th, the same surgeon performs carpal tunnel release surgery on the patient’s hand
- Carpal tunnel has nothing to do with hemorrhoids
- The carpal tunnel surgery gets modifier 79
Orthopedic Surgery Examples
Example 1: Right Knee Then Left Ankle
- Patient has arthroscopic knee surgery on the right knee on January 5th
- The procedure has a 90-day global period
- On February 10th, the patient falls and breaks their left ankle
- Same orthopedic surgeon performs surgery to fix the broken ankle
- The ankle fracture is completely unrelated to the knee surgery
- The ankle surgery gets modifier 79
Example 2: Left Shoulder Then Right Hand
- Patient has rotator cuff repair on the left shoulder on May 1st with a 90-day global period
- On June 15th, the patient develops trigger finger in their right hand
- Same surgeon performs surgical release for trigger finger
- Trigger finger is unrelated to shoulder surgery
- The trigger finger release gets modifier 79
Dermatology Examples
Example 1: Facial Skin Cancer Then Hand Warts
- Patient has Mohs surgery to remove skin cancer from their face on April 1st
- On April 25th, during the global period, the same dermatologist performs cryotherapy to remove warts from the patient’s hand
- Warts are unrelated to skin cancer removal
- The wart removal gets modifier 79
Example 2: Back Mole Then Leg Abscess
- Patient has excision of a large mole on their back on February 1st
- On March 10th, during the global period, they develop an abscess on their leg
- Same doctor performs incision and drainage of the abscess
- The abscess is unrelated to the mole removal
- The abscess drainage gets modifier 79
Gynecology Examples
Example 1: Hysterectomy Then Cervical Biopsy
- Patient has hysterectomy on July 1st with a 90-day global period
- On August 15th, the same gynecologist performs colposcopy and cervical biopsy for abnormal pap smear findings
- The cervical findings are unrelated to the hysterectomy
- The colposcopy gets modifier 79
Example 2: Ovarian Cyst Then Breast Biopsy
- Patient has surgery for ovarian cyst removal on March 1st
- On April 10th, during the global period, the same surgeon performs breast biopsy for a suspicious lump
- The breast biopsy is unrelated to the ovarian surgery
- The breast biopsy gets modifier 79
Eye Surgery Examples
Example 1: Right Eye Then Left Eye Cataract
- Patient has cataract surgery on the right eye on May 1st
- On May 20th, during the global period, the same ophthalmologist performs cataract surgery on the left eye
- Surgery on a different eye for the same condition is typically considered unrelated
- The second eye surgery gets modifier 79
Example 2: Eyelid Repair Then Eyelid Cyst Removal
- Patient has eyelid ptosis repair on June 1st
- On July 10th, during the global period, the same surgeon performs chalazion excision to remove a cyst on the eyelid
- The chalazion is unrelated to the ptosis repair
- The chalazion excision gets modifier 79
| Specialty | Original Surgery | Later Unrelated Procedure | Time Between | Why Unrelated |
| General Surgery | Gallbladder removal | Hernia repair | 6 weeks | Different organs, different problems |
| Orthopedics | Right knee arthroscopy | Left ankle fracture repair | 5 weeks | Different joints, different sides |
| Dermatology | Facial skin cancer removal | Hand wart removal | 3 weeks | Different locations, different conditions |
| Gynecology | Hysterectomy | Breast biopsy | 6 weeks | Different organs, different problems |
| Ophthalmology | Right eye cataract surgery | Left eye cataract surgery | 3 weeks | Different eyes |
Insurance Company Rules for Modifier 79
Understanding how insurance companies view and process modifier 79 helps you use it in ways that avoid claim denials.
How Claims Get Checked
When an insurance company receives a claim with modifier 79, their computer system checks several things:
Step 1: Check for Active Global Period The system looks for another procedure by the same provider for the same patient that is currently in a global period. It searches recent claims to find procedures with global periods.
Step 2: Check Procedure Relationship If a procedure in a global period is found, the system looks at whether the new procedure code is related or unrelated to the previous procedure.
Insurance companies have lists in their systems that identify procedures typically related to each other.
Step 3: Determine Action If the system determines the procedures are unrelated, the claim processes for payment with modifier 79 noted. If the system questions the relationship between procedures, the claim might be held for manual review.
Step 4: Manual Review if Needed A claims examiner looks at the procedure codes, diagnosis codes, and sometimes the medical records to determine if the procedures are truly unrelated. The examiner decides whether to approve or deny the claim.
Common Reasons Claims Get Denied
Claims with modifier 79 get denied for several common reasons:
- Insurance company determines the procedures are related, not unrelated
- Documentation does not support that the procedures address different medical problems
- The diagnosis codes are the same or very similar, suggesting related procedures
- The new procedure appears to be treating a complication of the original surgery
- The provider used modifier 79 when the procedures were actually planned stages
Understanding these denial reasons helps you avoid them by using modifier 79 only when truly appropriate and documenting clearly why procedures are unrelated.
What Insurance Looks for in Medical Records
Insurance companies look closely at medical necessity when modifier 79 is used. They want to make sure:
- The second procedure was truly needed for a separate medical problem
- The procedure was not just elective or cosmetic work done at a convenient time
- The medical problem requiring the second procedure is clearly different from the first surgery
Strong documentation includes:
- What symptoms or findings made the second procedure necessary
- Why the second procedure could not wait until after the global period ended
- How the second procedure addresses a medical problem unrelated to the first surgery
Getting Authorization Before Surgery
Some insurance companies require prior authorization for procedures even when modifier 79 will be used. The fact that a procedure is unrelated to a previous surgery does not remove authorization requirements.
When scheduling a procedure during another procedure’s global period:
- Check whether prior authorization is needed
- Obtain authorization before performing the procedure
- Note on the authorization request that modifier 79 will be used due to an unrelated surgery being in its global period
Common Mistakes with Modifier 79
Several common mistakes happen when providers use modifier 79. Avoiding these mistakes improves claim acceptance rates.
Mistake 1: Using 79 for Related Procedures
The most common mistake is using modifier 79 when procedures are actually related. Providers sometimes think that because procedures are on different body parts or done at different times, they must be unrelated. But if they address the same underlying medical problem or one is a result of the other, they are related.
Wrong Example: A patient has back surgery that causes nerve damage leading to foot drop. Later surgery to correct the foot drop uses modifier 79.
Why This is Wrong: The foot drop surgery is related to the back surgery because it treats a consequence of the back surgery. Do not use modifier 79. This might not be billable separately at all.
Correct Approach: Do not bill separately, or if billable, use modifier 78 for related return to surgery.
Mistake 2: Forgetting to Use 79 When Needed
The opposite mistake is forgetting to add modifier 79 when it is needed. A provider bills an unrelated procedure during a global period without the modifier. The claim denies because the insurance system sees it as part of the global period.
What Happens:
- Claim submitted without modifier 79
- Insurance denies as part of global period
- Provider must correct and resubmit with modifier 79
- Payment is delayed
How to Avoid: Always check whether a patient is in any global periods before billing new procedures. Keep a tracking system showing which patients have active global periods.
Mistake 3: Confusing 79 with 78 or 58
Providers sometimes use the wrong modifier from among 78, 79, and 58. Each modifier has specific situations when it applies.
Quick Decision Guide:
- Is the procedure related to the original surgery treating complications or problems? Use modifier 78
- Is the procedure part of a planned treatment with multiple stages? Use modifier 58
- Is the procedure completely unrelated to the original surgery? Use modifier 79 Taking time to determine which category applies prevents using the wrong modifier.
Mistake 4: Poor Documentation
Using modifier 79 with weak documentation causes problems. The medical record must clearly show why the procedures are unrelated.
What Good Documentation Includes:
- The medical problem requiring the new procedure
- How it differs from the original surgery reason
- That the new problem is not related to the original surgery
- Why the new procedure is medically necessary
What Poor Documentation Looks Like:
- Vague notes that do not explain the new problem
- No mention of how the new problem differs from the original surgery
- Minimal explanation of medical necessity
Mistake 5: Not Checking Global Period Status
Sometimes providers use modifier 79 when it is not needed because they think a global period is still active when it actually ended. Or they fail to use it because they do not realize a global period is active.
How to Avoid:
- Before billing any procedure, check whether the patient has any procedures in global periods
- Know when those global periods end
- Keep a calendar or tracking system
- If billing during a global period for an unrelated procedure, add modifier 79
- If billing after the global period ended, no modifier is needed
| Common Mistake | What Goes Wrong | How to Fix It |
| Using 79 for related procedures | Claim denial or audit problems | Carefully check if procedures are truly unrelated |
| Forgetting 79 when needed | Claim denies as bundled service | Always check global period status before billing |
| Using wrong modifier (78 or 58 instead of 79) | Wrong payment amount or denial | Learn the differences between modifiers |
| Poor documentation | Claim denial on review or audit | Document clearly why procedures are unrelated |
| Not tracking global periods | Wrong modifier use or missing it | Create a system to track patient global periods |
Medicare Rules for Modifier 79
Medicare has specific rules about modifier 79 that may differ slightly from commercial insurance rules. Providers billing Medicare should understand these details.
What Medicare’s Global Surgery Package Includes
Medicare defines what is included in the global surgery package very specifically. The package includes:
Pre-Operative Services:
- Visits starting the day before surgery for major procedures
- Visits the day of surgery for minor procedures
Surgical Services:
- The surgical procedure itself
- Immediate post-surgical services
Post-Operative Services:
- Complications that do not require return to the operating room
- Post-operative visits during the global period
- Post-surgical pain management by the surgeon
- Supplies except those with their own codes
- Removing sutures
What Is NOT Included (Can Be Billed Separately):
- Unrelated procedures (use modifier 79)
- Treatment of underlying conditions that led to the surgery
- Diagnostic tests not part of normal post-operative care
- Services clearly unrelated to the surgery
How to Find Medicare Global Periods
Medicare assigns global periods to all procedures in their physician fee schedule. You can look up any procedure code in Medicare’s database to find its global period indicator.
Medicare Global Period Indicators:
- 000 = Zero-day global period
- 010 = Ten-day global period
- 090 = Ninety-day global period
- MMM = Service not subject to global period concept
- XXX = Global concept does not apply
- YYY = Carrier determination
- ZZZ = Add-on code
When billing Medicare, use their global period assignments even if other insurance companies might use different global periods for the same procedure.
Medicare’s Computer Checks
Medicare’s claims processing system contains edits that check modifier 79 usage:
What the System Checks:
- Another procedure by the same provider for the same patient is in a global period
- Whether the new procedure code is typically related or unrelated to the previous procedure
- Medicare’s coding relationships database
What Happens Next:
- If edits are satisfied, claim processes for payment
- If system questions the modifier 79 usage, claim suspends for manual review
- Medicare contractor reviews the claim
- May request medical records before making payment decision
Medicare Documentation Rules
Medicare requires documentation supporting modifier 79 usage. The medical record must show:
- The new procedure addresses a different diagnosis
- It is not related to the original surgery
- It was medically necessary for the separate diagnosis
- It was not part of planned staged procedures
Medicare audits look at modifier 79 usage. If modifiers are used incorrectly:
- Medicare may require refunds of overpayments
- May apply penalties for repeated incorrect billing
- May conduct more frequent audits
Modifier 79 in Different Medical Specialties
Different medical specialties use modifier 79 in ways specific to their types of procedures. Understanding common scenarios in each specialty helps with correct usage.
General Surgery
General surgeons frequently use modifier 79 when patients need multiple different surgeries close together.
Common Scenarios:
- Patient has appendectomy, then later needs gallbladder removal
- Patient has hernia repair, then later needs colon surgery
- Patient has abdominal surgery, then later needs breast surgery
These surgeries are on different organs for different diagnoses, making them unrelated.
Orthopedic Surgery
Orthopedic surgeons see patients who have surgery on one joint, then later need surgery on a different joint during the global period.
Common Scenarios:
- Right knee surgery followed by left shoulder surgery
- Hip replacement followed by hand surgery
- Ankle fracture repair followed by carpal tunnel release Different joints for different problems qualify for modifier 79. Plastic Surgery
Plastic surgeons doing reconstructive work might have planned stages that use modifier 58. But if they perform an unrelated cosmetic procedure during a reconstruction global period, that would need modifier 79.
Common Scenarios:
- Breast reconstruction after mastectomy, then unrelated facial procedure
- Burn reconstruction on arm, then unrelated mole removal on leg
Primary Care and Family Medicine
Primary care physicians who perform minor procedures may use modifier 79 when doing different minor procedures during global periods.
Common Scenarios:
- Skin biopsy on the arm followed by joint injection in the knee
- Lesion removal on back followed by ingrown toenail removal
- Wart removal followed by cyst drainage
Family medicine doctors doing obstetric care have a global maternity care package. Any unrelated procedures during the postpartum global period need modifier 79.
Eye Doctors (Ophthalmology)
Eye doctors commonly use modifier 79 when operating on both eyes separately.
Common Scenarios:
- Cataract surgery on one eye followed by cataract surgery on the other eye
- Glaucoma surgery on right eye followed by retinal surgery on left eye
- Eye surgery for one condition followed by surgery for different condition in same or different eye
Stomach and Intestine Doctors (Gastroenterology)
GI doctors performing procedures through endoscopy may use modifier 79 when doing different procedures during global periods.
Common Scenarios:
- Colonoscopy with biopsy followed by upper endoscopy
- Polyp removal followed by hemorrhoid banding
- Lower GI procedure followed by upper GI procedure
Skin Doctors (Dermatology)
Dermatologists frequently perform multiple procedures on different skin areas.
Common Scenarios:
- Removal of cancerous lesion on face followed by removal of benign lesion on back
- Mohs surgery for skin cancer on one area followed by cryotherapy on different area
- Skin biopsy on one location followed by excision on different location
When procedures address unrelated skin problems in different body locations during global periods, modifier 79 applies.
| Specialty | Typical Modifier 79 Situation | Key Point |
| General Surgery | Different abdominal organs operated on | Different organs = unrelated |
| Orthopedics | Different joints operated on | Different joints = usually unrelated |
| Plastic Surgery | Reconstruction plus unrelated cosmetic work | Must not be part of reconstruction plan |
| Primary Care | Different minor procedures | Different body areas and problems |
| Ophthalmology | Different eyes operated on | Each eye treated separately |
| Gastroenterolog y | Upper GI plus lower GI procedures | Different parts of digestive system |
| Dermatology | Different skin lesions in different locations | Different locations and diagnoses |
Teaching Staff About Modifier 79
Healthcare providers and billing staff need training on modifier 79 to use it correctly. Good training prevents billing errors and claim denials.
What to Include in Training
Basic Information:
- What modifier 79 means in simple language
- When it should be used
- When it should not be used
- Clear examples of correct use
Comparison with Similar Modifiers:
- How modifier 79 differs from modifier 78
- How modifier 79 differs from modifier 58
- Decision tree for choosing the right modifier
Practical Skills:
- How to check if a patient is in a global period
- How to add the modifier to claims properly
- What documentation is needed
Real Examples: Use actual cases from your practice’s specialty to make training relevant. Show examples where modifier 79 was correctly used and examples where it would be wrong to use it.
Quick Reference Tools for Billing Staff Create simple tools staff can use when coding: Flowchart for Modifier 79 Decision:
- Is the patient in a global period from a previous procedure?
- If no, do not use modifier 79
- If yes, go to question 2
- Is it the same doctor doing the new procedure?
- If no, do not use modifier 79
- If yes, go to question 3
- Is the new procedure unrelated to the previous one?
- If no, consider modifier 78 or 58 instead
- If yes, use modifier 79
Common Scenarios List:
Create a list showing when modifier 79 does and does not apply:
Use Modifier 79:
- Knee surgery then shoulder surgery (different joints)
- Gallbladder removal then hernia repair (different organs)
- Right eye surgery then left eye surgery (different eyes)
Do Not Use Modifier 79:
- Knee surgery then infection treatment at knee surgical site (related – complication)
- First stage of reconstruction then second stage (related – planned stages)
- Surgery then routine follow-up visit (normal post-op care)
Regular Training Updates
Provide ongoing education about modifiers:
Monthly Reminders: Include modifier 79 information in regular billing meetings. Review any denials that occurred related to the modifier.
When Problems Occur: Use claim denials as teaching opportunities. When a modifier 79 claim gets denied, review what went wrong with the whole billing team so everyone learns from the mistake.
Annual Review: Conduct annual comprehensive training covering all commonly used modifiers including 79. Update staff on any rule changes.
New Staff Training: Make sure new billing staff receive thorough training on modifiers before they start coding claims independently.
Checking Your Modifier 79 Use
Healthcare organizations should monitor modifier 79 usage to make sure it is being used correctly.
Internal Checking Process
Regular internal checks should review a sample of claims with modifier 79:
What to Check:
- Are the procedures truly unrelated?
- Is the global period timing correct?
- Does documentation support the modifier use?
- Was the correct modifier chosen versus 78 or 58?
What to Do with Findings:
- Errors found should lead to staff retraining
- Correct future billing
- If overpayments occurred due to wrong modifier use, refunds to insurance companies may be necessary
Warning Signs of Problems
Certain patterns suggest possible problems with modifier 79 usage:
Red Flags to Watch For:
- Very high frequency of modifier 79 use (might indicate using it for related procedures)
- Using modifier 79 on procedure pairs that are typically related
- Inconsistent use (sometimes adding it and sometimes not for similar situations)
- Multiple denials of modifier 79 claims
Monitor for these warning signs. When they appear, investigate to find out why.
Checking Medical Record Documentation
Review the medical record documentation supporting modifier 79 claims:
Documentation Should Show:
- Why procedures are unrelated
- The separate medical necessities for each procedure
- That the second procedure is not treating problems from the first
Weak Documentation Requires:
- Physician education about documentation needs
- Improved documentation templates
- Better communication between clinical and billing staff
What Might Change in the Future
Medical billing rules change over time. Understanding possible future changes helps providers stay prepared.
Rule Changes That Happen
Medicare and insurance companies sometimes update global period assignments for procedures:
What Can Change:
- A procedure that currently has a 90-day global might change to 10-day global
- New procedures get added with global period assignments
- Existing procedures might have global periods removed
How to Stay Current:
- Review annual updates to fee schedules
- Read coding guideline updates
- Update billing systems when global periods change
- Train staff on changes
Billing Softwares Getting Smarter
Billing software is becoming better at automatically checking whether modifiers are needed:
Future Technology:
- Systems may automatically suggest adding modifier 79 when billing a procedure during another procedure’s global period
- Automated checks might flag when modifier seems to be used incorrectly
- Better integration between clinical documentation and billing systems
Important Note: While computers help, human review remains important. Automated systems cannot always tell whether procedures are truly related or unrelated. Billing staff need to understand the rules to verify what computers suggest.
New Payment Models
Healthcare is slowly moving toward different payment methods:
Changes Happening:
- Some move from fee-for-service to value-based payment
- Bundled payments for episodes of care
- Accountable care organization models
Impact on Modifier 79: Traditional fee-for-service billing will continue alongside newer payment models for many years. Modifier 79 will remain important for traditional Medicare and commercial insurance billing.
More Focus on Documentation
The trend is toward requiring more detailed documentation:
What This Means:
- Insurance companies can more easily review electronic health records
- Documentation gets checked more carefully
- Providers using modifier 79 should expect close review of whether procedures are truly unrelated
How to Prepare: Strong, clear documentation becomes increasingly important for supporting modifier 79 usage and protecting against audits.
Conclusion
Modifier 79 is an important tool in medical billing. It allows providers to receive appropriate payment for unrelated procedures performed during the global period of a previous surgery. Understanding when and how to use this modifier correctly prevents claim denials and helps practices get paid properly.
Key Points to Remember
What Modifier 79 Does:
- Tells insurance a procedure is unrelated to a previous surgery
- Allows payment for the new procedure during the global period
- Only applies when same physician does both procedures
When to Use It:
- Same doctor performs new procedure
- During global period of previous surgery
- New procedure is completely unrelated to first surgery
- Different medical problems being treated
When NOT to Use It:
- Procedures are related to each other
- Different doctor performs new procedure
- Normal follow-up care
- Planned staged procedures (use modifier 58 instead)
- Return to surgery for complications (use modifier 78 instead)
Whether you work in a private practice, hospital, billing company, or coding department, understanding modifier 79 helps you handle surgical billing correctly. Using this modifier right when needed and avoiding it when not appropriate supports the financial health of your organization while following billing rules properly.
Take time to learn the rules. Train your staff well. Check your work. Document clearly. When you do these things, modifier 79 becomes a helpful tool rather than a source of confusion and denials.
