KX modifier

kx modifier, modifier kx, kx modifier medicare

KX modifiers are just one in a group of two digit codes linked to a CPT code which provides further description and extra details about the service that was provided. You’re likely familiar with them if you’re a physical therapist working with a Medicare insurance plan. Like many aspects of billing, PTs are told when to apply the modifier, but may not have a good understanding of why it is used. In this article we will discuss the Medicare threshold system, the purpose of the KX modifier and how to apply it correctly.

What is the KX modifier?

In addition to the KX modifier, some of the other common 2 digit modifiers include the modifier 59, modifier XE, modifier XS, modifier XU and modifier XP. Each modifier serves a specific purpose and should be appended to a claim at a certain time.

Medicare provides physical, occupational and speech therapy services that are deemed “medically necessary.” The KX modifier is linked to the threshold or cap system within Medicare insurance plans.

Since 2018, Medicare has created thresholds for therapy coverage that a therapist is allowed to exceed by appending claims with a KX modifier. Prior to 2018 there was a hard cap on how much therapy a patient with Medicare insurance could receive. The change in 2018 came as a result of the Bipartisan Budget Act and expanded access to physical, occupational and speech therapy services for our clients.

So while the Bipartisan Budget Act expanded the number of visits a patient with Medicare can access, a system of thresholds is in place to monitor spending on therapy services and to hold therapists to a standard of medically necessary care. 

When the patient reaches the first threshold the therapist will append each claim with a KX modifier. When they reach the second threshold, a targeted medical review process is initiated.  Medicare determines the monetary threshold each year using the Medicare Economic Index

The Medicare Economic Index is a measure of inflation faced by physician practices relative to their practice costs and wage levels. It is updated yearly to adjust for the changes in inflation and practice costs like rent, medical equipment, non-physician employee compensation and so forth.

Because of its relation to the Medicare Economic Index, the threshold levels for therapy services for Medicare patients changes each year. When a patient has reached the first threshold or “cap,” a therapist must append each claim with a KX modifier. 

Let’s look at how the thresholds or “caps” have changed over the years. 
For calendar year 2023, the KX modifier threshold amounts are:               
  • PT and SLP services combined: $2,230

  • OT services alone: $2,230


For calendar year 2022, the KX modifier threshold amounts were:                      
  • PT and SLP services combined: $2,150

  • OT services alone: $2,150


For calendar year 2021, the KX modifier threshold amounts were:                 
  • PT and SLP services combined: $2,110

  • OT services alone: $2,110

Looking at these numbers you may notice that occupational therapy claims have their own threshold while physical and speech therapy claims are combined. This used to be a big issue before 2018 when services were limited by a hard cap, especially for patients needing multidisciplinary services like a patient who experienced a stroke and needed a long course of PT and speech therapy. 

Now, with this newer system, the patient has access to any services that are determined to be medically necessary but PTs and SLPs need to be aware that they may need to apply the KX modifier to their claims earlier than OTs.

Once the patient reaches $3,000 in claims for PT/SLP or OT services, a targeted medical review kicks in to ensure these services are still medically necessary and Medicare dollars are being utilized judiciously. While this can sound scary, it really is an important checks and balance system and therapists can limit claim denials by documenting appropriately.

Start Your Free Trial Now

Documentation to support the KX Modifier

Many of our patients will need therapy services beyond the first threshold. This especially applies to patients with chronic medical conditions, unstable presentations or who are receiving multidisciplinary services like physical and speech therapy who will reach that first threshold twice as fast as the OT threshold. 

Even a patient who underwent a surgery early in the year who needed 20 visits and then sprained their ankle and needed therapy later in the year can easily cross the first Medicare threshold. In these cases, it is up to the therapist to use their clinical judgment to determine when continued therapy is needed. 

Following these recommendations can help ensure your documentation supports the need for continued care:
  • Thoroughly document the functional limitations that your patient is experiencing and that you are addressing with your interventions.

  • Create functional goals that show the aim of your plan of care.

  • Utilize functional outcome measures that demonstrate functional limitations and can be readministered throughout the course of care to show both progress in response to therapy intervention as well as a continued functional limitations that necessitate therapy services.

  • Perform regular reassessments in which you document patient progress, update functional outcome measures and goals and document why skilled services are necessary to help the patient continue to progress toward functional improvements. It is helpful to state why your services are necessary versus discharging the patient to a home program to work independently.

Using the KX modifier at the right time is imperative to prevent insurance claim denials. Having a system in your practice to determine when the first threshold is met and to alert therapists so they can append the claim with the modifier is important. While documentation can take up a lot of a therapist’s time, making the extra effort to thoroughly document medical necessity, response to care and your clinical determination on why the patient should continue to receive treatment after the first threshold, stands between you and claim denials.


TheraPlatform, an all-in-one EHR, practice management and teletherapy tool for therapists can help make billing easy. They offer a 30-day, free trial with no credit card required. Cancel anytime.

More resources
Free video classes

Practice Management, EHR/EMR and Teletherapy Platform

Exclusive therapy apps and games

Start 30 Day FREE TRIAL
M54.6,  icd 10 thoracic pain, thoracic pain icd 10, thoracic back pain icd 10, icd 10 thoracic back pain, thoracic spine pain icd 10
Upper back pain ICD 10 code

M54.6 is the closest ICD-10 code for pain in the thoracic spine when treating a patient with pain located in the upper back. Learn how to best use this code.

modifier59, modifier59 for physical therapy,
Modifier 59

While billing and claim submission are not fun, learning about effective billing practices including how to use Modifier 59, can keep your practice profitable.

Subscribe to our newsletter