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Simplified Billing and Coding for Modifiers -59 and -XS

By November 21, 2023No Comments

Dermatology billing and coding can be a complex landscape to navigate.  Understanding the endless rules, regulations, and modifiers is challenging at best.   In this article, we’ll focus on two essential modifiers, -59 and -XS, and provide real-world scenarios to clarify when and how to use them. Mastering these modifiers is crucial for accurate billing, minimizing denials, and ensuring proper reimbursement.

Official AMA CPT Modifier Description

-59         Distinct Procedural Service

Under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-E/M services performed on the same day. Modifier 59 is used to identify procedures/services, other than E/M services, that are not normally reported together, but are appropriate under the circumstances.

Documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or organ system, separate incision/excision, separate lesions, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by ordinarily encountered or performed on the same day by the same individual. However, 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.

Note: Modifier 59 should not be appended to an E/M service. To report a separate and distinct E/M service with a non-E/M service performed on the same date, see modifier 25 in the CPT book to understand its use.


The Correct Coding Initiative (CCI)

Medicare publishes a document that is a comprehensive guide on the use of the 59 modifier.  Billing staff should review the article and understand its use.  Medicare National Correct Coding Initiative (NCCI) Edits


X Modifiers


Separate Encounter


Separate Practitioner


Separate Structure


Unusual Non-Overlapping Service


Usage of Modifier -59

In this scenario, use Modifier -59 to indicate that the surgical services billed are distinct procedures performed during the same visit.  See the below examples.


Modifier -59 – Example

A patient undergoes a minor surgical procedure to remove a benign lesion followed by a biopsy of another suspicious lesion during the same visit.

  • CPT Code for lesion removal: 11440 (Excision, other benign lesion)
  • CPT Code for biopsy: 11102 (Biopsy of skin, subcutaneous tissue, and mucous membrane)

Modifier -XS – Example

A patient visits the Dermatologist with a wart on his finger and several Actinic Keratosis on his forehead, both are treated with liquid nitrogen. You bill:

  • ICD-10 Code for Actinic Keratosis: L57.0
  • ICD-10 Code for Wart: B07.9

Modifier -XS – Example

Here, you should use Modifier -XS on the CPT codes to distinguish the two separate structures. Modifier XS indicates separate structures/lesions were treated, helping prevent claim denials due to bundling.

Gaining proficiency in coding modifiers such as -59 and -XS is essential for providers and billers, ensuring accurate reimbursement and reducing claim denials. By judiciously applying these modifiers in relevant situations, healthcare professionals can precisely convey the services provided and secure fair compensation for their efforts. Understanding these nuances in coding is a valuable asset in today’s complex landscape.

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If you are interested in speaking with our company about how we can maximize your collections while also improving your process, please contact us or call 888-434-4374.

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