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Modifier 25 vs 59 | Nym Automated Medical Coding Engine

Written by Chermanda Jackson, Medical Coding & Compliance Auditor | Nov 25, 2025 11:00:00 AM

Key Takeaways: Modifier misuse ranks among the top causes of claim denials, with modifiers 25 and 59 frequently confused despite serving distinct purposes—modifier 25 for separate E/M services and modifier 59 for distinct procedural services performed on the same day. Continue reading to learn about when to apply each modifier, common misuse scenarios that trigger payer audits, and how autonomous medical coding solutions eliminate modifier confusion while generating comprehensive documentation that supports every code assignment during audits and appeals.

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Modifier 25 Overview

Modifier 59 Overview

Key Differences

Common Misuse Scenarios

Compliance & Audit Tips

Modifier 25 Overview

CPT modifier 25 allows medical professionals to report separate evaluation and management (E/M) services that they perform on the same day as another service. The other service can be a significantly different E/M service or a procedure (1). 

To be able to use modifier 25, the separate E/M service has to go above and beyond the work that you might typically associate with the original procedure or service (2). If the work the medical professional performed was typical for the procedure or service they’re already billing for, there is no need to use modifier 25. 

Here are a few questions medical staff can ask themselves to help determine whether it’s appropriate to use modifier 25 under the E/M coding guidelines:

  • Did the provider perform and document a medically necessary E/M service separate from the original procedure or service?
  • Would this secondary E/M service be able to stand on its own as a billable service?
  • Did the E/M service yield a separate diagnosis? If not, did the E/M service require additional work that goes beyond what’s typically associated with the other procedure or service?

You don’t need to reach a separate diagnosis or use two different diagnosis codes to use modifier 25 (3). However, whether the medical provider reaches the same diagnosis or no diagnosis at all, the evaluation and management work must be separate from the procedure or service the patient came in for to justify the use of modifier 25. 

Modifier 59 Overview

By contrast, CPT modifier 59 applies when a medical professional provides two distinct procedural services on the same day that wouldn’t typically be grouped together but should be under the circumstances (4). 

The Current Procedural Terminology (CPT) from the AMA states that you should only use modifier 59 if there are no other established modifiers that could be appropriate. If there aren’t any other more descriptive modifiers available and modifier 59 applies, only then use modifier 59 (4). 

There are a few circumstances under which it makes sense to use Modifier 59 (5):

  • When treating two different sites or organ systems
  • When completing separate incisions or excisions
  • When conducting different sessions on the same day
  • When performing separate procedures in succession

Check the National Correct Coding Initiative (NCCI) before applying modifier 59 to make sure the edits do not prohibit doing so. 

Key Differences

The most obvious difference between modifier 25 vs. 59 is that modifier 25 deals with separate E/M services, while modifier 59 deals with non-E/M services or procedures (6). So, the first question to ask before using either of these modifiers is: Are you billing for E/M services or not?

Only use CPT modifier 25 if the medical professional provided separate E/M services on the same day as other services or procedures. Only use CPT modifier 59 if the medical professional completed a separate non-E/M service or procedure on the same day as another. Never add modifier 59 to E/M services. 

Common Misuse Scenarios

Professionals can end up misusing modifiers 25 or 59 by billing a service or procedure as “separate” when it’s actually part of the standard work associated with the patient's visit. For example, if a patient comes in for a colonoscopy and the provider checks in before the procedure to make sure it’s still necessary, those evaluation services are part of the standard pre-procedure care. The provider cannot bill those services separately from the colonoscopy using modifier 25. 

Another misuse scenario that comes up often is using modifier 59 when another modifier, such as XS (separate structure), is more appropriate. If the procedure is distinct because the medical provider performed it on a separate organ or structure in the patient’s body, that sounds like a scenario in which modifier 59 would apply. However, modifier XS is the more specific modifier, so it’s the one coders should use (4). 

Compliance & Audit Tips

It’s worth noting that insurance payers closely monitor high use of modifiers like 25 and 59. Frequently using these modifiers could get your claims flagged for additional review or denial. Make sure you have clear, complete documentation of all the services provided and procedures performed and clinical justification for all of them. Documentation is your strongest resource when dealing with audits or compliance issues.  

Apply these tips to ensure your charts meet compliance standards and help avoid auditing concerns:

  • Make sure you select the best, most applicable modifier for the services provided, and only use modifier 59 as a last resort (4). For example, modifiers XE or XS may be more appropriate than 59 in some similar circumstances.
  • Keep thorough documentation that shows why and how the two services or procedures performed on the same day are separate.  
  • Do not use modifiers to get around NCCI edits unless you’re certain that you have complete justification and medical documentation to support using the modifier you selected (4). 

Coding requirements change frequently. Staying on top of these changes can create significant administrative hassles for healthcare providers, leaving them with less time to focus on patient care. But failing to use the right codes creates compliance risks and increases the chances of costly claims denials. 

The solution is using an automated coding engine to support medical coding team members.

With Nym’s coding engine, charts go into the engine and get coded automatically before heading directly to the billing department. There’s no human intervention required. Nym also automatically generates traceable documentation justifying every code it assigns. You have access to comprehensive, transparent resources backing up your codes in case you need them for audits or denials in the future.

Sources

  1. Robeznieks, A. (17 August 2023). Setting the record straight on proper use of modifier 25. American Medical Association. Retrieved October 30, 2025, from https://www.ama-assn.org/practice-management/cpt/setting-record-straight-proper-use-modifier-25 
  2. How to Use Modifier 25. American Academy of Family Physicians. Retrieved October 30, 2025, from https://www.aafp.org/family-physician/practice-and-career/getting-paid/coding/evaluation-management/how-to-use-modifier-25.html 
  3. (September 2025). Evaluation and Management Services. Centers for Medicare & Medicaid Services. Retrieved October 30, 2025, from https://www.cms.gov/files/document/mln006764-evaluation-management-services.pdf 
  4. (February 2025). Proper Use of Modifiers 59, XE, XP, XS & XU. Centers for Medicare & Medicaid Services. Retrieved October 30, 2025, from https://www.cms.gov/files/document/proper-use-modifiers-59-xe-xp-xs-xu.pdf 
  5. Eramo, L. (25 July 2018). Coding tips: Modifiers -25, -26, and -59. Medical Economics. Retrieved October 30, 2025, from https://www.medicaleconomics.com/view/coding-tips-modifiers-25-26-and-59
  6. Ortiz, A. (29 July 2019). Solve Your 5 Biggest Modifier 59 Problems by Focusing on ‘Separate.’ Healthcare Training Leader. Retrieved October 30, 2025, from https://healthcare.trainingleader.com/2019/07/modifier-59/