Understanding Medicare Global Period Rules is one of the most important skills for surgeons, physicians, and billers. Yet it’s also one of the most confusing areas in Medicare surgery billing. Many providers unknowingly bill services that are already bundled into the global surgery package, which leads to automatic denials, payment reductions, and even Medicare audits.

I’ve personally worked with practices that lost thousands of dollars every month simply because they didn’t understand CMS global period rules or proper postoperative billing rules. After fixing their global days coding and applying the correct postoperative modifiers, their collections improved almost immediately.

In this complete guide, we’ll break down Medicare Global Period Rules explained, what’s included in the surgical package billing, which services you can bill separately, and exactly how to bill during global period without triggering surgery claim denials.

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What Are Medicare Global Period Rules?

So first, what exactly are Medicare Global Period Rules?

CMS created the global surgery package concept to bundle related services around surgery into one payment.

Instead of paying separately for:

• pre-op visits

• surgery

• routine follow-ups

Medicare combines everything into a single payment under bundled surgical services.

This system follows:

• CMS bundling edits

• surgical reimbursement rules

• strict Medicare compliance

The goal is to prevent duplicate billing and control healthcare costs.

If providers bill separately for services already included in the CPT global days, Medicare simply denies the claim.

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Types of Global Periods Under Medicare

Medicare assigns different global surgery periods (global days) to procedures. These categories determine how long postoperative care is bundled into the payment for a procedure and cannot be billed separately.

As someone working in medical billing and coding, I’ve seen many denials happen simply because the global period wasn’t verified before claim submission. Understanding global days is essential for accurate reimbursement and compliance.

0-Day Global

Used for: Minor procedures (e.g., simple lesion removal, diagnostic procedures)

What’s included:

• Preoperative services on the same day of the procedure

• The procedure itself

• Postoperative care provided on the same day only

Important Tip:
Any follow-up visits after the procedure day can usually be billed separately (if medically necessary and documented properly).

10-Day Global

Used for: Minor surgeries

What’s included:

• Preoperative services on the day of the procedure

• The surgery

• Postoperative care for 10 days

During these 10 days, routine follow-up visits related to the procedure are bundled and not separately payable.

Important Tip:
If a patient returns during the 10-day period for an unrelated issue, you may bill separately using modifier 24 (Unrelated E/M during postoperative period), with proper documentation.

90-Day Global

Used for: Major surgeries (e.g., joint replacement, abdominal surgery), Includes full postoperative billing rules coverage.

What’s included:

• One preoperative visit (usually the day before or day of surgery)

• The surgery itself

• All routine postoperative care for 90 days

If you’ve ever wondered “What is a 90-day global period?” it means that all normal recovery-related care for 90 days after surgery is bundled into the surgical payment and is not separately reimbursed.

Case Study:
Many claim rejections happen because providers try to bill routine post-op visits within the 90-day window. Only services that are unrelated, require a return to the OR (modifier -78), or are staged procedures (modifier -58) may qualify for separate payment.

MMM (Maternity)

MMM = Maternity Services

This applies to maternity-related procedures and follows special global rules. Routine prenatal, delivery, and postpartum care are typically bundled together under global OB billing.

Always verify the CMS global days list before submitting claims.

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What Services Are Included in the Global Surgical Package?

Under Medicare’s global surgical package guidelines, certain services are bundled into one single payment for the procedure. This means they cannot be billed separately because they are already included in the reimbursement.

Medicare Bundles the Following:

• Preoperative visits
  (One day prior for major procedures – 90-day global)

• Intraoperative services
  (All usual and necessary services during the surgery)

• Routine postoperative care

• Follow-up visits
  (Related to normal recovery)

• Minor supplies
  (Dressings, sutures, routine materials)

• Postoperative pain management
  (If managed by the surgeon and not a separate provider)

All of these fall under surgical package coding guidelines and are considered part of one comprehensive payment.

Why Billing These Separately Causes Claim Denials

When you submit a separate charge for a service that is already bundled into the global surgical package, Medicare’s system automatically flags it as included in the global period.

In simple terms:

👉 Medicare has already paid for those services within the surgical fee.
👉 Billing them again is considered duplicate or unbundled billing.
👉 The claim will either be denied or reduced.

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What Services Are NOT Included (Bill Separately)?

This is where many providers and billers get confused and where most denials happen.

While Medicare bundles routine surgical care into the global package, not every service during the global period is automatically included. Certain services can absolutely be billed separately, but only with proper documentation and correct modifier usage.

Services That Can Be Billed Separately

1. Unrelated E/M Visits

If the patient is seen during the global period for a condition completely unrelated to the surgery, you may bill the visit separately.

Required Modifier: -24
(Unrelated Evaluation & Management service during postoperative period)

💡 Example:
A patient had knee surgery (90-day global) but returns for hypertension management. This visit is separately billable with modifier -24.

2. New Conditions

If a new medical issue arises that is not connected to the surgical recovery, it can be billed separately — again with proper documentation.

Clear documentation must show:

• It is not related to the surgery

• It required separate evaluation and management

3. Diagnostic Tests

Imaging, labs, or other diagnostic services that are medically necessary and not bundled into the surgical payment can be billed separately.

💡 Real-World Tip:
Always confirm whether the diagnostic service is considered part of routine post-op care. Many payers follow Medicare guidelines but may have slight variations.

4. Complications Requiring Return to the OR

If the patient must return to the operating room for a related complication, this is separately payable.

Required Modifier: -78
(Return to the OR for related procedure during postoperative period)

Important:

• Payment is typically reduced

• The global period does not reset

This is one of the most misunderstood areas in surgical billing.

5. Staged or Planned Procedures

If a procedure was planned prospectively or is more extensive than the original procedure:

Required Modifier: -58
(Staged or related procedure during postoperative period)

Unlike modifier -78:

• The global period does reset

• Full payment is often allowed

6. Separate Significant E/M on Same Day as Procedure

If a provider performs a minor procedure and also provides a significant, separately identifiable E/M service:

Required Modifier: -25

Documentation must clearly show:

• The E/M service went beyond the usual preoperative evaluation

Why Correct Modifier Usage Under Medicare Is Critical

In my experience reviewing denied surgical claims, the issue usually isn’t that the service wasn’t payable, it’s that the modifier was missing or documentation didn’t support it.

Medicare systems automatically:

• Track global periods

• Bundle routine care

• Deny improperly unbundled services

Without the correct modifier, even a legitimately billable service will be denied.

Correct modifier usage under Medicare isn’t optional, it’s essential.

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Important Modifiers Used During Global Period

Modifiers are not just coding add-ons, they protect reimbursement during the CMS global period.

Medicare automatically tracks global days (0, 10, 90). If a service is performed during that timeframe, the system assumes it’s bundled, unless you clearly communicate otherwise using the correct modifier.

In my experience reviewing surgical denials, incorrect or missing modifiers are among the top causes of lost revenue during global periods.

Modifier 24 – Unrelated E/M During Global Period

Use When:
A patient is seen for a condition completely unrelated to the original surgery during the global period.

Example:
A patient had shoulder surgery (90-day global) but returns for diabetes management.

Key Rule:

• Must be unrelated

• Documentation must clearly support medical necessity

Without Modifier 24, the claim will likely deny as “included in global surgery payment.”

Modifier 25 – Significant, Separately Identifiable E/M (Same Day)

Use When:
An E/M service is provided on the same day as a minor procedure and is above and beyond the usual preoperative evaluation.

Example:
A patient presents with multiple complaints. The provider performs a minor procedure and also performs a full evaluation for a separate issue.

Important:
Documentation must clearly show the E/M service was significant and separate from the procedure work.

Modifier 25 is frequently audited, use carefully and accurately.

Modifier 58 – Staged or Planned Procedure

Use When:
A procedure during the global period was:

• Planned prospectively

• More extensive than the original procedure

• A therapy following a surgical procedure

Billing Impact:

• Typically paid at full allowable

• The global period resets

This modifier is often misunderstood but very important in surgical specialties.

Modifier 78 – Return to the Operating Room (Related)

Use When:
The patient returns to the OR for a related complication during the global period.

Example:
Postoperative bleeding requiring surgical intervention.

Billing Impact:

• Payment is usually reduced

• The global period does NOT reset

Many billers confuse Modifier 78 with 58, but reimbursement rules are very different.

Modifier 79 – Unrelated Procedure During Global Period

Use When:
A completely unrelated procedure is performed during the global period.

Example:
A patient recovering from knee surgery needs removal of a skin lesion.

Billing Impact:

• Paid separately

• A new global period begins for the new procedure

Proper documentation must clearly demonstrate that the procedure is unrelated.

Why Choosing the Correct Modifier Matters

Choosing the wrong modifier is one of the biggest causes of medical billing errors because:

• ❌ Claims get denied as bundled

• ❌ Payments get reduced incorrectly

• ❌ Audits become more likely

• ❌ Revenue cycle delays increase

From my billing experience, many “denied” services were actually payable, they were just coded without the correct modifier or lacked clear documentation.

Accurate modifier selection isn’t just coding, it’s compliance, revenue protection, and audit safety.

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How Medicare Reimbursement Works During the Global Period

Medicare does not pay separately for every service performed around a surgery. Instead, it pays one bundled amount for procedures assigned a global period (0, 10, or 90 days).

Understanding how this bundled payment works is critical for preventing denials and protecting reimbursement.

How Medicare Calculates Surgical Payment

Medicare reimbursement is based on:

RVUs (Relative Value Units)

Each CPT code has RVUs assigned for:

• Physician work

• Practice expense

• Malpractice expense

These components reflect the total resources required for the procedure, including pre-op, intra-op, and post-op care.

Conversion Factor

RVUs are multiplied by the annual CMS Conversion Factor to determine the final payment amount.

Global Surgery Reimbursement Rules

The assigned global period determines how long postoperative care is bundled into that single payment.

In simple terms:
Medicare has already factored routine follow-up care into the surgical RVUs.

What Happens During the Global Period?

Routine Visits Inside the Global Period = $0 Payment

If a patient returns for normal postoperative follow-up related to the surgery, Medicare considers it included.

The claim may:

• Deny as bundled

• Process with $0 reimbursement

• Show remark codes indicating “included in global payment”

This is one of the most common misunderstandings among newer providers, they expect payment for post-op visits, not realizing those visits were prepaid within the surgical RVUs.

A clear understanding of global surgery reimbursement rules is not just good billing practice, it’s essential for clean claims and strong revenue cycle performance.

Understanding this directly reduces claim denial prevention issues.

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Common Medicare Global Period Billing Mistakes

After reviewing surgical claims and audit reports over the years, I can confidently say that most global period denials are preventable. The problem usually isn’t Medicare being “strict”, it’s misunderstanding or poor tracking of global surgery billing guidelines.

These are frequent Medicare surgery billing guidelines problems I see during audits:

1. Billing Routine Postoperative Visits

Routine follow-up visits related to the surgery are already included in the global package.

Billing these visits separately results in:

• $0 payment

• Bundling denial codes

• Increased audit risk if repeated

If it’s normal recovery care, it’s already paid within the surgical RVUs.

2. Missing Modifier 24 or 79

When a patient is seen for an unrelated issue or undergoes an unrelated procedure during the global period, failing to attach the correct modifier is one of the fastest ways to get denied.

• Modifier 24 → Unrelated E/M

• Modifier 79 → Unrelated procedure

Without these, Medicare automatically assumes the service is related and bundles it.

3. Wrong Modifier Selection

This is more common than people realize.

Examples:

• Using Modifier 25 instead of 24

• Using Modifier 58 instead of 78

• Applying 78 when the service was actually unrelated (should have been 79)

Each modifier has different reimbursement consequences:

• Some reset the global period

• Some reduce payment

• Some require OR documentation

Incorrect selection can cause:

• Denials

• Underpayments

• Compliance red flags

4. Duplicate E/M Billing

Billing an E/M service on the same day as surgery without proper documentation and Modifier 25 is a common error.

Medicare assumes the preoperative evaluation is included unless documentation clearly shows:

• A significant, separately identifiable service

Duplicate or unsupported E/M billing is frequently flagged in audits.

5. Not Tracking Surgery Dates

One of the biggest operational mistakes is failing to track:

• Surgery date

• Global period length (0, 10, 90 days)

• Global end date

If your team isn’t tracking this accurately, claims will go out during the global window without appropriate modifiers, leading to avoidable denials.

In many practices, simply implementing a global period tracking system significantly reduces rejections.

These errors trigger how to avoid global period denials situations.

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Real-Life Scenarios

Understanding modifiers is one thing.
Knowing when to apply them in real clinical situations is what prevents denials.

Below are realistic global period medical billing scenarios I commonly see in surgical billing reviews, and how Medicare expects them to be coded.

Scenario 1: Planned Second Surgery

Situation:
A patient undergoes a staged reconstructive procedure. The second surgery was planned at the time of the original procedure.

Correct Modifier: Modifier 58

Why?

• The procedure was planned prospectively

• It’s part of the treatment plan

• It may be more extensive than the first

Billing Impact:

• Usually paid at full allowable

• The global period resets

💡 Common mistake: Using Modifier 78 instead of 58, which leads to reduced payment.

Scenario 2: Complication – Return to Operating Room

Situation:
A patient develops postoperative bleeding and must return to the OR during the global period.

Correct Modifier: Modifier 78

Why?

• It’s related to the original surgery

• It required a return to the operating room

Billing Impact:

• Payment is typically reduced

• The global period does NOT reset

💡 In audits, I often see this miscoded as Modifier 58, which can create compliance concerns because 58 implies a planned procedure.

Scenario 3: New Injury During Postoperative Period

Situation:
A patient recovering from shoulder surgery falls and fractures their wrist.

Correct Modifier: Modifier 79

Why?

• Completely unrelated to the original surgery

• Separate condition requiring treatment

Billing Impact:

• Paid separately

• A new global period begins for the new procedure

Documentation must clearly show no clinical relationship to the original surgery.

Scenario 4: Unrelated Office Visit

Situation:
A patient within a 90-day global period comes in for uncontrolled hypertension management.

Correct Modifier: Modifier 24

Why?

• E/M service is unrelated to the surgery

• Separate medical necessity exists

Without Modifier 24, Medicare will bundle the visit automatically.

Modifier 58 vs 78 vs 79 — Medicare Decision Logic

Here’s a simple way I train billing teams to think about it:

 

When reviewing claims, I always ask:

1. Is it related to the original surgery?

2. Was it planned?

3. Did the patient return to the OR?

4. Does documentation clearly support the modifier?

These scenarios clearly show modifier 58 vs 78 vs 79 Medicare decisions.

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Medicare Global Period Quick Checklist for Billers

Over the years, I’ve seen that most global period denials aren’t caused by complex regulations, they’re caused by skipped verification steps. A simple pre-submission checklist can dramatically reduce revenue loss and compliance risk.

Before submitting any claim during a Medicare global period, confirm the following:

1. Check CPT Global Days

• Verify whether the procedure has 0, 10, or 90 global days.

• Confirm using the CMS Physician Fee Schedule (PFS).

• Document the surgery date and calculate the global end date.

🔎 Tip: Never assume the global period — always verify.

2. Confirm Bundled vs. Non-Bundled Services

Ask:

• Is this routine postoperative care?

• Is it related to normal recovery?

If yes, it is bundled and not separately payable.

3. Apply the Proper Modifier

If the service qualifies for separate payment, ensure the correct modifier is attached:

• 24 – Unrelated E/M

• 25 – Significant, separate E/M same day

• 58 – Staged/planned procedure

• 78 – Return to OR (related)

• 79 – Unrelated procedure

Incorrect modifier usage is one of the most common denial triggers.

4. Validate Documentation

Even when a modifier is correct, payment depends on documentation that:

• Clearly supports medical necessity

• Demonstrates unrelated status (if applicable)

• Specifies return to OR when required

• Distinguishes separate E/M work

In audit reviews, documentation gaps are often the real issue, not the coding itself.

5. Review Surgical Reimbursement Rules

Understand:

• Whether payment will be reduced (Modifier 78)

• Whether the global period resets (Modifier 58 or 79)

• Whether the visit is included in RVUs

Knowing the reimbursement impact prevents surprise underpayments.

6. Prevent CMS Bundling Edits Issues

Medicare systems automatically apply:

• Global period tracking

• Bundling edits

• Duplicate service checks

If the claim does not clearly justify separate payment, it will default to bundled processing.

A proactive internal review step can significantly reduce CMS edit-related denials.

If managing this internally feels overwhelming, you can always schedule a demo with experienced billing experts who specialize in Medicare surgical reimbursement optimization.

With the right knowledge and process, postoperative billing becomes predictable, clean, and denial free.

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FAQs

1. What are Medicare Global Period Rules?

Medicare Global Period Rules define how surgical services are bundled and paid together during 0, 10, or 90 days after surgery.

2. What is included in the Medicare global surgical package?

Preoperative visits, the surgery itself, and routine postoperative care are included.

3. Which modifiers are used during the global period?

Common modifiers include 24, 25, 57, 58, 78, and 79.

4. Can providers bill office visits during the global period?

Only unrelated or separately identifiable visits can be billed with proper modifiers.

5. Why are global period claims denied?

Denials happen due to bundled services, missing modifiers, or poor documentation.