What Are Medical Coding Modifiers?

A medical coding modifier is two characters (letters or numbers) appended to a CPT^® or HCPCS Level II code. The modifier provides additional information about the medical procedure, service, or supply involved without changing the meaning of the code. Medical coders use modifiers to tell the story of a particular encounter.

For instance, a coder may use a modifier to indicate a service did not occur exactly as described by a CPT^® or HCPCS Level II code descriptor, but the circumstance did not change the code that applies. A modifier also may provide details not included in the code descriptor, such as the anatomic location of the procedure. Some payer programs may have modifiers that apply only when you’re reporting codes in connection with those programs, as well.

The CPT^® code book Introduction provides these additional examples of when a modifier may be appropriate:

• The service or procedure has both professional and technical components.
• More than one provider performed the service or procedure.
• More than one location was involved.
• A service or procedure was increased or reduced in comparison to what the code typically requires.
• The procedure was bilateral.
• The service or procedure was provided to the patient more than once.

Proper use of modifiers is important both for accurate coding and because some modifiers affect reimbursement for the provider. Omitting modifiers or using the wrong modifiers may cause claim denials that lead to rework, payment delays, and potential reimbursement loss.

CPT^® Modifiers

The American Medical Association (AMA) holds copyright in CPT^®. CPT^® modifiers are generally two digits, although performance measure modifiers that apply only to CPT^® Category II codes are alphanumeric (1P-8P).

These are examples of some of the most commonly used CPT^® modifiers:

• 25 Significant, separately identifiable evaluation and management service by the same physician or other qualified health care professional on the same day of the procedure or other service
• 26 Professional component
• 59 Distinct procedural service

You’ll find CPT^® modifiers listed in your CPT^® code book. A complete online CPT^® resource also should include CPT^® modifiers. Note that CPT^® code books often include an abbreviated list of HCPCS Level II modifiers.

HCPCS Level II Modifiers

HCPCS Level II codes and modifiers are maintained by the Centers for Medicare & Medicaid Services (CMS). HCPCS Level II modifiers are alphanumeric or have two letters.

Below are some examples of HCPCS Level II modifiers:

• E1 Upper left, eyelid
• TC Technical component; under certain circumstances, a charge may be made for the technical component alone; under those circumstances the technical component charge is identified by adding modifier ‘tc’ to the usual procedure number; technical component charges are institutional charges and not billed separately by physicians; however, portable x-ray suppliers only bill for technical component and should utilize modifier tc; the charge data from portable x-ray suppliers will then be used to build customary and prevailing profiles
• XS Separate structure, a service that is distinct because it was performed on a separate organ/structure

You can find HCPCS Level II modifier lists in HCPCS Level II code books and in online coding resources. Because the HCPCS Level II code set is not copyrighted, the modifiers are also publicly available on CMS’ Alpha-Numeric HCPCS site and HCPCS Quarterly Update site.

Pricing Modifiers and Informational Modifiers

In addition to separating modifiers based on whether they’re from the CPT^® or HCPCS Level II code set, modifiers are also categorize by type. Two important categories are pricing modifiers (also called payment-impacting modifiers or reimbursement modifiers) and informational modifiers.

Pricing Modifiers

A pricing modifier is a medical coding modifier that causes a pricing change for the code reported. The Multi-Carrier System (MCS) that Medicare uses for claims processing requires pricing modifiers to be in the first modifier position, before any informational modifiers. On the CMS 1500 claim form, the appropriate field is 24D (shown below). You enter the pricing modifier directly to the right of the procedure code on the claim. Most providers use the electronic equivalent of this form to bill Medicare for professional (pro-fee) services.

Claims that do not have the pricing modifier in the first position may encounter processing delays. To assist with proper reporting and modifier placement, individual payers may provide lists that distinguish pricing modifiers from informational modifiers for their claims. For instance, the WPS Government Health Administrators (WPS GHA) site includes a Pricing Modifier Fact Sheet that not only lists pricing modifiers, but also identifies which of those modifiers you should put in a secondary position if another pricing modifier is required for the code.

Informational Modifiers

An informational modifier is a medical coding modifier not classified as a payment modifier. Another name for informational modifiers is statistical modifiers. These modifiers belong after pricing modifiers on the claim.

Note that informational modifiers may affect whether a code gets reimbursed, so they may be relevant to payment, despite the name “informational.” For instance, coders often use modifier 59 to override Medicare’s National Correct Coding Initiative (NCCI) Procedure-to-Procedure (PTP) edits, bringing in payment for both codes in the code edit pair. Although you would not receive payment for the Column 2 code of the edit without modifier 59 on one of the codes from the edit pair, you may find modifier 59 classified as an informational modifier rather than a payment modifier. To return to our WPS GHA example, the payer lists modifier 59 as an informational modifier.

One payer’s list of pricing and informational modifiers may not match another’s list, so medical coders need to stay current on individual payer policy to avoid incorrect modifier placement that could affect claim processing.

NCCI Modifiers

An NCCI PTP-associated modifier is a modifier that Medicare and Medicaid accept to bypass an NCCI PTP edit under appropriate clinical circumstances. Bypassing or overriding an edit is also called unbundling.

Modifier 59, referenced in the previous section, is just one of the modifiers that can bypass an NCCI edit. Identical NCCI PTP-associated modifier lists are shown in the National Correct Coding Initiative Policy Manual for Medicare Services available on CMS’ NCCI edits page and in the National Correct Coding Initiative Manual for Medicaid Services available on the Medicaid NCCI reference documents page.

Table 1 shows the complete listing of NCCI PTP-associated modifiers. The categories (Anatomic Modifiers, Global Surgery Modifiers, and Other Modifiers) are how Medicare and Medicaid divide these modifiers.

While each of these modifiers is important, a few deserve special attention because they’re among the most used (or misused). Below is an overview of these modifiers.

NCCI Modifier 25: Separate E/M

When a patient has a separate E/M service along with a procedure or other service on the same day by the same provider, you may report that E/M code separately for reimbursement by appending modifier 25 Significant, separately identifiable evaluation and management service by the same physician or other qualified health care professional on the same day of the procedure or other service.

Based on the descriptor, an E/M encounter must meet the criteria below to qualify for separate reporting using modifier 25.

Significant, Separately Identifiable E/M Service

Many coders find that determining whether an E/M service is significant and separately identifiable is the most problematic requirement for modifier 25 use. The documentation must clearly show that the provider performed extra E/M work beyond the usual work required for the other procedure or service on the same date. In other words, if you removed all the documentation represented by the code for the other procedure or service, would the remaining documentation support reporting an E/M code?

Regarding diagnoses for these encounters, the Medicare and Medicaid NCCI manuals say the diagnosis can be the same for the procedure/service and separate E/M (both manuals include this in Chapter I.D). Although separate diagnoses are not required, experienced coders have found that linking one ICD-10-CM code to the procedure/service code and another ICD-10-CM code to the E/M code may speed claim processing. The separate ICD-10-CM codes make the distinct reasons for the E/M and other procedure or service more obvious. You should report different diagnosis codes, however, only if the documentation supports them.

Same Physician or Other Qualified Healthcare Professional

To interpret the “same physician” requirement correctly, medical coders must remember that Medicare follows this rule found in Medicare Claims Processing Manual, Chapter 12, Section 30.6.5:

Physicians in the same group practice who are in the same specialty must bill and be paid as though they were a single physician. If more than one evaluation and management (face-to-face) service is provided on the same day to the same patient by the same physician or more than one physician in the same specialty in the same group, only one evaluation and management service may be reported unless the evaluation and management services are for unrelated problems. Instead of billing separately, the physicians should select a level of service representative of the combined visits and submit the appropriate code for that level.

Same Day of the Procedure or Other Service

Determining whether an E/M service occurred on the same date of service as another procedure or service is typically straightforward. But keep in mind some points related to Medicare’s global surgery rules.

You may append modifier 25 to an E/M code reported on the same date as a minor surgical procedure code, which is a code with global period indicator 000 or 010 on the Medicare Physician Fee Schedule (MPFS), according to Chapter I.E of the Medicare NCCI manual. The manual also states you may append modifier 25 to an E/M code performed on the same date as a code with a global indicator of XXX.

Before you report an E/M code on the same date as a procedure code with indicator 000 (0-day global), 010 (10-day global period), or XXX (global rules not applicable), consider that those codes include the pre-, intra-, and post-procedure work involved. You should not report an E/M code for that work, even with modifier 25 appended.

Medicare also includes the decision to perform a minor surgical procedure in the procedure code, the NCCI manual states. So, you shouldn’t report a separate E/M code for that work. When you’re reporting an E/M code representing the decision to perform a major surgery (one with a 090 global indicator, which represents a 90-day global period), you should append modifier 57 Decision for surgery, and not modifier 25.

Modifier 25 Example

Here is an example of when to use modifier 25 based on a scenario in Medicare Claims Processing Manual, Chapter 12, Section 40.1.C. Suppose the physician sees a patient with head trauma and decides the patient needs sutures. After checking allergy and immunization status, the physician performs the procedure. An E/M is not separately reportable in this scenario. But, if the physician performs a medically necessary full neurological exam for the head trauma patient, then reporting a separate E/M with modifier 25 appended may be appropriate.

NCCI Modifiers 59 and X{EPSU}: Distinct Service

Modifier 59 Distinct procedural service is a medical coding modifier that indicates documentation supports reporting non-E/M services or procedures together that you normally wouldn’t report on the same date. Appending modifier 59 signifies the code represents a procedure or service independent from other codes reported and deserves separate payment.

Like modifier 25, modifier 59 is difficult to master because it requires determining whether the code is truly distinct and separately reportable from other codes. The CPT^® definition of modifier 59 advises that the modifier may be appropriate for a code when documentation shows at least one of the following:

• A separate patient encounter or session
• A different procedure or surgery
• A different anatomic site or organ system
• A separate incision/excision
• A separate lesion
• A separate injury (or area of injury in the case of an extensive injury)

The CPT^® definition also states that you should not use modifier 59 when a more descriptive modifier is available. For instance, you may be able to use anatomic modifiers to demonstrate that procedures occurred at separate sites on the body.

As an example, the first-quarter 2021 Medicare NCCI PTP edits include the edit pair 29827 Arthroscopy, shoulder, surgical; with rotator cuff repair and 29820 Arthroscopy, shoulder, surgical; synovectomy, partial. The edit has a modifier indicator of “1,” which means you may bypass the edit in appropriate clinical circumstances. An article about modifier 59 in MLN Matters SE1418 states you shouldn’t report 29820 (with or without an NCCI modifier) “if both procedures are performed on the same shoulder during the same operative session. If the procedures are performed on different shoulders, modifiers RT and LT should be used, not Modifiers 59 or -X{EPSU}.”

X{EPSU} Modifiers

When considering whether to append modifier 59, medical coders must factor in the so-called X{EPSU} modifiers. These are HCPCS Level II modifiers that Medicare created as more specific alternatives to modifier 59:

• XE Separate encounter, a service that is distinct because it occurred during a separate encounter
• XP Separate practitioner, a service that is distinct because it was performed by a different practitioner
• XS Separate structure, a service that is distinct because it was performed on a separate organ/structure
• XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service

In the announcement about the creation of the X{EPSU} modifiers in 2014, CMS stated, “Usage to identify a separate encounter is infrequent and usually correct; usage to define a separate anatomic site is less common and problematic; usage to define a distinct service is common and not infrequently overrides the edit in the exact circumstance for which CMS created the edit in the first place.” The use of the more specific modifiers shows the reason the service was separate or distinct in a way that modifier 59 does not. This specificity gives auditors, payers, and providers more information to help them determine which type of reporting is prone to errors.

Medicare still accepts modifier 59, but check with individual payers to see which modifiers they prefer for a distinct procedural service.

NCCI Medicare Global Package Modifiers

Modifiers also play an important role in reporting procedures and services performed during a surgical code’s global period, which is the timeframe when the global surgical package concept applies.

Medicare’s global surgical package is a policy that incorporates payment in the surgery code fee for necessary, routine services before, during, and after a procedure. The policy applies to work performed by same-specialty members of the same group.

This article has already explained that global period indicators are relevant to modifier 25 and 57 use. Below are additional modifiers NCCI identifies as Global Surgery Modifiers, which means the modifiers may allow you to identify that a service is separately payable even though it occurred during a surgery’s global period.

Modifier 24: Unrelated E/M

Modifier 24 Unrelated evaluation and management service by the same physician or other qualified health care professional during a postoperative period is appropriate for use only on E/M codes and only for services unrelated to the original procedure (the one with the global period).

Note that using modifier 24 to report an E/M related to the underlying disease process may be appropriate. Suppose, for example, that a biopsy reveals a malignant tumor. The patient returns during the biopsy’s global period for suture removal and, on the same date, has a distinct E/M visit with the physician to discuss the diagnosis and treatment options. The work and time related to suture removal and routine post-biopsy care are not separately reportable, but you can report the E/M service using modifier 24.

Medicare’s Global Surgery Booklet supports this use of modifier 24, stating, “Treatment for the underlying condition or an added course of treatment which is not part of normal recovery from surgery” is not included in Medicare’s global surgical package. The CPT^® Surgery section guidelines provide similar wording: “Care of the condition for which the diagnostic procedure was performed or of other concomitant conditions is not included and may be listed separately.”

Modifier 58: Staged/Related Procedure

Another important global package modifier is modifier 58 Staged or related procedure or service by the same physician or other qualified health care professional during the postoperative period.

Medicare’s Global Surgery Booklet states that using modifier 58 signifies that performing a procedure or service during the postoperative period was one of the following (the CPT^® code book uses similar language):

• Planned prospectively or at the time of the original procedure
• More extensive than the original procedure
• For therapy following a diagnostic surgical procedure

You should append modifier 58 to the code for the staged or related procedure. A new postoperative period begins when you report that next procedure in the series.

Modifier 78: Unplanned Return to OR

When the patient returns to the operating or procedure room during the global period for an unplanned but related procedure, you should append modifier 78 Unplanned return to the operating/procedure room by the same physician or other qualified health care professional following initial procedure for a related procedure during the postoperative period.

A common use for modifier 78 is to report treatment for complications. The global surgical package does not include “treatment for postoperative complications which requires a return trip to the operating room (OR),” according to Medicare Claims Processing Manual, Chapter 12, Section 40.1.B.

The manual goes on to explain that an “OR for this purpose is defined as a place of service specifically equipped and staffed for the sole purpose of performing procedures. The term includes a cardiac catheterization suite, a laser suite, and an endoscopy suite. It does not include a patient’s room, a minor treatment room, a recovery room, or an intensive care unit (unless the patient’s condition was so critical there would be insufficient time for transportation to an OR).”

As Medicare Administrative Contractor (MAC) Palmetto GBA explains in its modifier 78 page, “If the subsequent surgery is related to the initial surgery but does not require a return to the operating room, and both are performed by the same surgeon, the subsequent surgery cannot be submitted separately. The global fee for the initial surgery includes additional related surgical procedures that do not require a return to the operating room.”

The CPT^® Surgery section guidelines are not as specific as the Medicare global rules regarding the operating/procedure room requirements. The CPT^® guidelines state that “complications, exacerbations, recurrence, or the presence of other diseases or injuries requiring additional services should be separately reported.” Because rules may differ, medical coders should check individual payer policies on reporting complications treated during the global period.

Modifier 79: Unrelated Procedure

For unrelated procedures during the postoperative period, the CPT^® code set provides modifier 79 Unrelated procedure or service by the same physician or other qualified health care professional during the postoperative period.

Reporting the same code for the initial procedure and the “unrelated” procedure may be appropriate, as this example of proper modifier 79 use shows: Suppose a patient has a right-eye cataract extraction reported using 66984 Extracapsular cataract removal with insertion of intraocular lens prosthesis (1 stage procedure), manual or mechanical technique (eg, irrigation and aspiration or phacoemulsification); without endoscopic cyclophotocoagulation. The same patient then has a left-eye cataract extraction (again, 66984) by the same physician during the global period for the first procedure. You should append modifier 79 to the code for the second procedure. Although both procedures require the same code, they are unrelated because each surgery was on a different eye.

Modifiers on the MPFS

The final group of modifiers covered here relate to the MPFS, which is funded by Medicare Part B. The MPFS lists fee maximums Medicare uses to pay physicians and other healthcare professionals on a fee-for-service basis. MPFS relative value files of course include relative value units (RVUs), but those files also provide information essential to proper use of the modifiers below for Medicare claims.

Modifiers 26 and TC: Professional and Technical Components

Medicare (along with many other payers) splits some codes into professional and technical components. For services like radiologic exams where the entity performing the test and the interpreting provider are often different, having separate professional and technical components simplifies reporting and payment. CPT^® code 71046 Radiologic examination, chest; 2 views is an example of a code that has both professional and technical components.

Using modifier 26 Professional component allows the provider to claim reimbursement for the provider’s work, including supervision, interpretations, and reports. PC is an abbreviation for professional component, but medical coders must take care not to accidentally append modifier PC Wrong surgery or other invasive procedure on patient in place of modifier 26.

Modifier TC Technical component represents costs like paying technicians and paying for equipment, supplies, and the space used.

The PCTC IND (PC/TC Indicator) column in the MPFS relative value files reveals whether a code has a PC/TC split and whether you may append modifiers 26 and TC to the code. With 10 distinct indicators, medical coders benefit from referring to a current list of MPFS modifier indicator definitions to ensure they’re using the modifiers correctly.

If a code has both a technical and a professional component and you report the code without using modifier 26 or TC, you’re claiming that you’ve earned reimbursement for both components. This type of code with a PC/TC split is called a global code (not to be confused with the global period and global surgical package). For codes that accept modifiers 26 and TC, the MPFS RVU spreadsheet provides RVUs and indicators specific to the global code and the individual components. The global service rate equals the sum of the rates for the two components.

Modifier 53: Discontinued Procedure

In addition to modifiers 26 and TC, the Medicare relative value files includes modifier 53 Discontinued procedure. Four colonoscopy codes (44388, 45378, G0105, and G0121) have one row for the code and one row for the code with modifier 53. The reason is that Medicare wants contractors to pay a consistent amount for those colonoscopy codes with modifier 53 appended.

CPT^® guidelines state that appending modifier 53 is appropriate when a patient is scheduled and prepared for a total colonoscopy, but “the physician is unable to advance the colonoscope to the cecum or colon-small intestine anastomosis due to unforeseen circumstances.”

Modifier 50: Bilateral Procedure

The MPFS includes a BILAT SURG (Bilateral Surgery) column that identifies how payment will differ if you report the code bilaterally. “Bilateral surgeries are procedures performed on both sides of the body during the same operative session or on the same day,” states Medicare Claims Processing Manual, Chapter 12, Section 40.7.

To indicate a procedure was bilateral, it may be appropriate to append modifier 50 Bilateral procedure. But as the definition of bilateral indicator “1” shows, MACs check for multiple ways of reporting bilateral procedures, including modifier 50, modifiers RT Right side and LT Left side, or 2 units:

1: 150% payment adjustment for bilateral procedures applies. If the code is billed with the bilateral modifier or is reported twice on the same day by any other means (e.g., with RT and LT modifiers, or with a 2 in the units field), base the payment for these codes when reported as bilateral procedures on the lower of: (a) the total actual charge for both sides or (b) 150% of the fee schedule amount for a single code. If the code is reported as a bilateral procedure and is reported with other procedure codes on the same day, apply the bilateral adjustment before applying any multiple procedure rules.

Modifier 51: Multiple Procedures

The MULT PROC (Multiple Procedure) column in the Medicare relative value files is connected to modifier 51 Multiple procedures. However, your MAC and many other payers may instruct you not to append modifier 51 to codes. The payer will apply the multiple-procedure fee reduction rules based on the codes reported and which of the nine possible MULT PROC indicators the fee schedule assigns to the code.

Consequently, for those payers that do not accept modifier 51, the MULT PROC column offers information about expected payment rather than about whether to use modifier 51. As an example of how this column affects payment, this is Medicare’s definition for multiple-procedure indicator “2”:

2: Standard payment adjustment rules for multiple procedures apply. If procedure is reported on the same day as another procedure with an indicator of 1, 2, or 3, rank the procedures by fee schedule amount and apply the appropriate reduction to this code (100%, 50%, 50%, 50%, 50% and by report). Base the payment on the lower of (a) the actual charge, or (b) the fee schedule amount reduced by the appropriate percentage.

Pre-Op, Intra-Op, and Post-Op Modifiers

The MPFS splits the work required for a surgery into the PRE OP (Preoperative Percentage), INTRA OP (Intraoperative Percentage), and POST OP (Postoperative Percentage) columns, which show how much of the fee each portion of the surgical work earns in cases where the same provider is not responsible for every aspect of care.

To alert the payer that different providers are involved, CPT^® provides these modifiers:

• 54 Surgical care only
• 55 Postoperative management only
• 56 Preoperative management only

Review payer rules for proper use of these modifiers. For instance, the Medicare Global Surgery Booklet clarifies that modifier 55 is appropriate only when there has been a transfer of care. You’ll use the surgery date as the date of service and can only use the modifier if the code has a global period of 10 days or 90 days.

Modifiers for Multiple Surgeons

The MPFS relative value files also include columns to indicate Medicare’s code-specific policies on modifier use and payment when multiple providers perform a procedure at the same session.

The CO-SURG (Co-surgeons) column is related to modifier 62 Two surgeons. Medicare’s Global Surgery Booklet provides these examples:

• A procedure requires two physicians of different specialties to perform it. Each reports the code with modifier 62 appended
• Two surgeons simultaneously perform parts of a procedure, such as for a heart transplant or bilateral knee replacements. Again, each surgeon reports the code with modifier 62 appended.

The TEAM SURG (Team Surgery) column is connected to modifier 66 Surgical team. This modifier is appropriate when more than two surgeons of different specialties perform a procedure. Each surgeon bills the code with modifier 66 appended.

The ASST SURG (Assistant at Surgery) column provides information related to these modifiers:

• 80 Assistant surgeon
• 81 Minimum assistant surgeon
• 82 Assistant surgeon (when qualified resident surgeon not available)
• AS Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery

The ASST SURG indicator will let you know whether payment for the additional provider is permitted, not permitted, or possibly permitted if documentation supports medical necessity.

With modifier 62, the Medicare fee for each co-surgeon is 62.5% of the global surgery fee schedule amount. For team surgeons using modifier 66, the Global Surgery Booklet advises that claims must have enough information to allow the MAC to determine pricing “by report.” For assistant-at-surgery services by physicians, the Medicare rate is 16% of the surgical payment. These examples prove yet again that proper use of medical coding modifiers is essential both for coding precision and for accurate payment.

CPT^® and HCPCS Level II Modifier FAQs

Last Reviewed on Jan 25, 2021 by AAPC Thought Leadership Team