Published 3/1/2015
Mary LeGrand, RN, MA, CCS-P, CPC

Modifier 59 Revisited

In anticipation of the “X” subset modifiers

In August 2014, the Centers for Medicare & Medicaid Services (CMS) identified modifier 59 as the most widely used modifier, noting that providers can use it to indicate that a code represents a service that is separate and distinct from another service with which it would usually be considered to be bundled. It also introduced a subset of “X” modifiers for modifier 59, but provided few specifics on the appropriate use of these modifiers. Since then (in January 2015), CMS has issued instructions to continue to use modifier 59.

This column reviews the importance of modifier 59 and explains why CMS created the new “X” subset modifiers.

Concerns of overuse
Nearly a decade ago (November 2005), an audit by the Office of Inspector General (OIG) found that 40 percent of code pairs billed with modifier 59 in fiscal year 2003 did not meet program requirements, resulting in $59 million in improper payments. The report noted that the code pairs did not meet program requirements either for documentation or for distinct services. OIG noted that, in 15 percent of code pairs, modifier 59 was used inappropriately because the services were not distinct from each other.

This issue has remained a topic of concern. “Because it can be so broadly applied,” wrote CMS, “some providers incorrectly consider it to be the ‘modifier to use to bypass National Correct Coding Initiative (NCCI).’”

In January 2015, CMS explained that the August 2014 transmittal “was intended to inform system developers that healthcare systems would need to accommodate the new modifiers.” This is good to know because it gives practices some breathing room to ensure that physicians, coding staff, and billing staff know when to use modifier 59.

NCCI edits
NCCI edits—also known as NCCI Procedure to Procedure (PTP) edits—identify code combinations, reported as Column 1 and Column 2 codes (
Table 1). CMS considers the Column 2 code to be a “subset” of the Column 1 code, and the two codes are not reportable together unless specific requirements are met. In most situations, it is incorrect to use a modifier to bypass the edit to receive payment for both procedures.

For example, as Table 1 shows, CPT code 20550 (injection tendon sheath) is inclusive to CPT code 20605 (drain/inject joint bursa), if they are performed at the same site (such as for the injection of the anesthetic agent prior to the intermediate joint injection). This does not reflect an accurate coding example because the injection of the anesthetic agent is not separately reportable. However, CMS identified an abuse pattern and created the edit to ensure proper claims payment.

If an orthopaedic surgeon performs an injection to the right wrist and also performs an injection to the flexor tendon sheath of the left index finger, both codes are reportable and a modifier will be necessary to “bypass” the edit. The documentation of medical necessity of both procedures (diagnosis codes) and the documentation of two separate procedure notes will support reporting both codes as well as the appropriate use of the modifier. Although either modifier 59 or a finger modifier (F2) would be acceptable with the lesser valued code (20550) today, as CMS moves to the use of the “most specific modifier,” the F2 would be more appropriate.

Remember, if an NCCI PTP edit does not exist, modifier 59 is not required.

More specific modifiers
Modifier 59 has always been identified as the “Distinct Procedural Service Modifier.” CMS has stated that modifier 59 is defined for use in a wide variety of circumstances, such as to identify different encounters, different anatomic sites, and distinct services. According to CMS, use of modifier 59 to identify a separate encounter is infrequent and usually correct, while usage to define a separate anatomic site is less common and problematic. On the other hand, usage to define a distinct service is common and frequently overrides the edit in the exact circumstance for which the edit was initially created.

According to the American Medical Association’s Current Procedural Terminology (CPT) manual, “when another, already established modifier is appropriate, it should be used rather than modifier 59. Only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used.” This is consistent with AAOS coding instructions as well.

The following modifiers are more specific according to several CMS carriers’ webinars on subset modifiers. However, carriers may have different modifier rules and keeping current can be challenging.

Modifier 50
Modifier 50—bilateral procedures—is more specific when an orthopaedic surgeon performs bilateral knee injections (reported as 20610-50). However, the format for reporting bilateral procedures varies by carrier, so it is important to follow payer instructions.

Right (RT) and left (LT) modifiers
CMS considers the RT and LT modifiers to be more specific when an orthopaedic surgeon performs a right knee arthroplasty and an injection to the left knee during the same operative session. The surgeon reports 27447 RT and 20610 LT. Payers vary on the acceptance of these informational modifiers and may require modifier 59 in addition to the anatomic modifiers (27447 RT and 20610-59, LT).

Modifier 76
Recently, some CMS carriers have announced that modifier 76 (repeat procedure by the same physician or other qualified healthcare provider) should be appended to a second duplicate code instead of modifier 59 when no other modifier works. Although some carriers say to use modifier 76, others say to report units. This becomes confusing because not all CMS carriers follow the same rules related to modifier 76 and reporting on surgical services.

Many private payers do not recognize modifier 76 on the same day on surgical CPT codes. For example, the orthopaedic surgeon performed a right knee injection and right shoulder injection. In this scenario, modifier 50 does not work, modifier 51 does not work, and the RT/LT modifiers do not work. Thus, the surgeon reported 20610 and 20610-59. Because the exact same CPT code was reported twice, CMS considered it a duplicate code. Instead of using modifier 59 (which indicates same procedure, separate location or structure), some carriers say to use modifier 76, while others say to use units.

CMS does not want modifier 59 used in this scenario; however, it can be used for private payers who do not follow CMS instructions.

Finger and toe modifiers
CMS and physicians agree that the finger (FA-F9) and the toe (TA-T9) modifiers are more specific than modifier 59. However, CMS has required the use of both the finger modifiers and modifier 59 when a physician reports the same CPT code twice in the same session, such as when repairing the flexor digitorum superficialis tendon in the left index and left middle finger. The F modifiers alone (26356 F1 and 26356 F2) should suffice, and to minimize the risk of overusing modifier 59, submit these codes with the anatomic finger modifiers only.

CMS subset modifiers
CMS introduced the new subset modifiers for use instead of modifier 59. Never submit both modifier 59 and the X modifier on the same CPT code.

XE—Separate encounter, a service that is distinct because it occurred during a separate encounter. This modifier should only be used to describe separate services performed during different encounters on the same date of service when a PTP edit exists between the CPT codes being reported.

XS—Separate structure, a service that is distinct because it was performed on a separate organ/structure. This modifier should only be used to report services performed on the same date by the same physician on different organs/structures when a PTP edit exists between the CPT codes being reported.

XP—Separate practitioner, a service that is distinct because it was performed by a different practitioner. This modifier should only be used to report services performed on the same date by the same physician (or a physician of the same specialty or group) performed at the same encounter when a PTP edit exists between the CPT codes being reported by each of the physicians.

XU—Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service.

These four new subset modifiers will never be reported with modifier 59 and should never be required if one of the “more specific” modifiers are appropriate. If an NCCI PTP edit does not exist, CMS carriers have stated that modifier 59 should not be appended nor will any of the subset modifiers be required.

The NCCI PTP edits apply to physicians (surgeons) of the same group and same specialty when services are performed on the same day. If two surgeons of differing groups perform both services and one of the services is a Column 2 code, CMS will process the claim for both surgeons and will expect that medical necessity was supported for both providers to perform the independent procedures. It is expected that billing practices such as this will fall under some scrutiny by CMS.

CMS assumes correct CPT coding rules are followed when codes are submitted and the edits will be bypassed only when the rules are met (ie, separate organ system, separate encounter).

An upcoming issue of AAOS Now will address more detailed information on when and how to use the modifiers following direction from CMS. In the meantime, staff should take the following steps:

  1. Make sure someone in the office receives e-newsletters from the CMS carrier and signs up for the MLN Connects CMS newsletter.
  2. Watch Explanation of Benefit forms closely when a service is denied or rejected by CMS as inclusive to another code. Make sure all remark codes are reviewed to understand the reason for denial or rejection.
  3. Ensure accurate coding of all services.
  4. Do not use modifier 59 to bypass an NCCI PTP edit if the services are overlapping and do not meet one of the criteria defined by the X modifier definitions.
  5. Survey private payers to determine if they will require the X modifiers. If yes, determine their process for publishing their code combinations that meet the definition of modifier 59 or the appropriate X modifier.
  6. Do not report modifier 59 to CMS if a more appropriate modifier works. Do not append modifier 59 to a code combination if an NCCI PTP does not exist.

Mary LeGrand, RN, MA, CCS-P, CPC, is a senior consultant with KarenZupko & Associates, Inc., who focuses on coding and reimbursement issues in orthopaedic practices. Information in this article has been reviewed by members of the AAOS Coding, Coverage, and Reimbursement Committee.


  1. OIG Report [PDF]
  2. CMS guidance [PDF]
  3. 2015 AMA Professional Edition CPT current procedural terminology. 2014 American Medical Association. Page 680.