Blog Post

When to Use the KX Modifier

Here’s what you need to know to correctly apply the KX modifier to avoid claim denials and ensure payment. Click here to learn more.

Erica McDermott
5 min read
October 8, 2018
image representing when to use the kx modifier
Share this post:


Get the latest news and tips directly in your inbox by subscribing to our monthly newsletter

In the months since the elimination of the hard cap on therapy services, it seems like rehab therapists are more confused than ever about when they should affix the KX modifier versus issue an Advance Beneficiary Notice of Noncoverage (ABN). The truth of the matter is that not much has changed operationally since the Medicare therapy cap repeal—aside from the name of the cap (i.e., what was once the “hard cap” is now called the “soft cap” or “threshold”). To keep things simple, though, here’s what you need to know about correctly using the KX modifier to avoid claim denials and ensure payment from patients when appropriate:

Apply the KX modifier when you provide medically necessary services above the soft cap.

Therapists should continue to affix the KX modifier to all medically necessary services above the designated limit ($2,010 in 2018), thus signaling Medicare to pay the claim. That means you must continue to track your patients’ progress toward the threshold so you know when to affix the modifier. It also means your documentation should fully support the medical necessity of your services, because Medicare performs targeted reviews for claims over the secondary threshold of $3,000 (when providers meet certain criteria such as having a high claim denial rate or aberrant billing practices). But, that certainly doesn’t mean you should shy away from providing—and billing Medicare for—services above the threshold as long as they are, in fact, medically necessary. That could unnecessarily delay your patients’ progression through their care.

Use NCDs and LCDs to determine medical necessity.

What Medicare considers “reasonable and necessary” isn’t always cut and dried; instead, it varies based on on both National Coverage Determinations (NCDs) and Local Coverage Determinations (LCDs). And it’s up to you to know the current NCDs and LCDs that govern your practice. To start, you can download the Medicare NCD Manual here and use the search tool here to identify the LCDs associated with your geographic region.

Issue an ABN for services above the soft cap that you do not believe are medically necessary.

If your patient would like to receive services that are not medically necessary, issue an ABN prior to performing those services. That stands whether or not your patient has reached the soft cap. Once you have a signed ABN on file, you should still submit claims to Medicare—with a GA modifier, which will trigger Medicare to reject those claims. Then, after you receive the denial from Medicare, you can collect payment for those services directly from your patients.

If you still have questions about when to use the KX modifier—and when to issue an ABN—download our free, super-simple ABN decision chart here.


KLAS award logo for 2024 Best-in-KLAS Outpatient Therapy/Rehab
Best in KLAS  2024
G2 rating official logo
Leader Spring 2024
Capterra logo
Most Loved Workplace 2023
TrustRadius logo
Most Loved 2024
Join the PXM revolution!

Learn how WebPT’s PXM platform can catapult your practice to new heights.

Get Started
two patients holding a physical therapist on their shoulders