KX Modifier Threshold 2026: $2,480, What It Attests To, and What Your Record Has to Show

What are the 2026 KX modifier threshold amounts?

CMS sets the amounts each year in a transmittal to the Medicare Administrative Contractors. For 2026 that is Transmittal 13437, Change Request 14252, issued 30 October 2025, effective 1 January 2026, implemented 5 January 2026.

Three things about those numbers that get misread

The threshold is per beneficiary, per calendar year. CMS’s own phrase is "annual per-beneficiary incurred expenses amounts." PT and SLP charges add together against one $2,480; OT has its own $2,480. A patient receiving PT and OT in the same year has two running totals.

The KX threshold is indexed every year by the Medicare Economic Index, which is why the number changes each January and why CMS issues a new transmittal every autumn. The MR threshold is the exception: it remains at $3,000 until CY 2028, at which time it will be updated by the MEI.

And the number is not a cap. Section 50202 of the Bipartisan Budget Act of 2018 repealed the therapy caps from 1 January 2018 and preserved the former cap amounts as thresholds above which claims must include the KX modifier. Care does not stop at $2,480. The claim form starts saying something new.

What does the KX modifier attest to?

The Medicare Claims Processing Manual, Chapter 5, section 10.3.3, puts it in three bullets. By appending KX the provider is attesting that the services billed are reasonable and necessary services that require the skills of a therapist, are justified by appropriate documentation in the medical record, and qualify for an exception using the automatic process exception.

Read the second one twice. The modifier is a statement about the record, not about the patient. If the chart cannot support the medical necessity of the services above the line, adding KX does not repair the chart. It makes the claim assert something the chart does not.

The same chapter answers the question every clinic asks at some point, which is whether to add KX to every claim once the patient has a qualifying condition. Section 10.3.1: "Routine use of the KX modifier for all patients with these conditions will likely show up on data analysis as aberrant and invite inquiry." That is CMS saying no, in its own words, and telling you how it will notice.

On the other side, section 10.3.3: "If a claim is submitted without KX modifiers and the cap is exceeded, those services will be denied." A missing KX is a denial you can see coming from the running total.

The audit that started in April 2026

On 15 April 2026 CMS approved Recovery Audit Contractor topic 0228, Therapy Claims Billed with KX Modifier, Medical Necessity, and Documentation Requirements. Three facts from the CMS page: the review type is Complex, meaning records are requested and read by a reviewer rather than matched automatically; the provider types are Outpatient Hospital and Professional Services, so private practices are in scope; and the jurisdiction is all A/B MACs, meaning every state.

The description, verbatim: "Documentation will be reviewed to determine if therapy meets Medicare coverage criteria, meets applicable coding guidelines, and/or is medically reasonable and necessary. Appropriate use of modifier KX will be evaluated. Use of modifier KX indicates that the clinician attests that services at, and above, the therapy threshold are medically necessary and reasonable, with justification for continued therapy documented in the patient’s medical record."

The affected code lists are the codes you bill every day, including 97110, 97112, 97116, 97140, 97530 and 97535 for physical therapy, the 97165 to 97168 evaluation codes for occupational therapy, and 92507, 92523, 92526, 96125, 97129 and 97130 for speech-language pathology. The full lists are on the CMS page.

Before April 2026 the KX attestation was read by a contractor when a claim happened to be selected. Now there is a named national review whose stated purpose is to read it. That changes what the sentence "the record justifies continued care" costs when it is not true.

What the record has to show

The attestation points at four documents. Each one has a rule that says when it is due and what it must contain.

The certification clock is where the attestation most often fails

Section 220.1.3 of the Medicare Benefit Policy Manual, Chapter 15: the physician or non-physician practitioner shall certify the initial plan as soon as it is obtained, or within 30 days of the initial therapy treatment. If the order to certify is verbal, it must be followed within 14 days by a signature to be timely. Recertifications should be signed whenever the need for a significant modification of the plan becomes evident, or at least every 90 days after initiation of treatment under that plan.

There is mercy in the same section: certifications are acceptable without justification for 30 days after they are due, and a delayed certification accompanied by a reason for the delay satisfies the requirement at any later date. A late signature is recoverable. A missing one is what the manual calls a technical denial.

The progress report is the document that carries the justification. CMS’s own booklet, MLN905365 (September 2025), says progress reports justify medical necessity and are required at least once every 10 treatment days. Treatment days, not visits scheduled and not calendar days. When a reviewer reads a KX claim, the most recent progress report is the page that either says why a therapist’s skills are still required or does not.

In order, a reviewer opens: the certified plan of care for the dates billed, the certification or recertification signature and its date, the most recent progress report covering the period, and the treatment notes for each date on the claim. If you can lay those four on a desk for any patient above $2,480 and each one says what its section of the manual requires, the attestation is true. If one is missing, the running total is not the problem.

What happens at $3,000?

The $3,000 Medical Record threshold is where targeted medical review begins. It is not a second cap and it does not mean every claim over $3,000 is reviewed. The Claims Processing Manual, section 10.3.2, describes the mechanism in one sentence: "Documentation justifying the services shall be submitted in response to any Additional Documentation Request (ADR) for claims that are selected for medical review." Selection is targeted; the request, when it comes, is for the same four documents.

Where the money is actually lost

One Medicare Administrative Contractor publishes its prepayment review results by code, with reason codes and percentages. Palmetto GBA’s Jurisdiction J Part A review of CPT 97110 (therapeutic exercise) for October to December 2024 covered Alabama, Georgia and Tennessee: 1,237 claims reviewed, 168 denied, a 14% claim denial rate. The top five reasons were no physician certification or recertification (20%), units billed more than ordered (19%), insufficient documentation (17%), requested records not submitted timely (13%), and no documentation of medical necessity (10%).

This is one contractor, one code, one quarter, three states. It is not a national therapy denial rate, and CMS does not publish one. What it shows is the shape of the problem: the top reason is a signature with a date, the second is a plan of care that did not say how many units, and the fourth is a records request that went unanswered. None of them is a clinical judgement call. All of them are things the record either contains or does not, which is exactly what the KX attestation says it contains.

What this means for the invoice today

The modifier lives on the claim form. The invoice is what the patient sees, and for a patient above the threshold it should show the same dates and the same services as the claim, because a reviewer who asks for records may ask for both. Carearoo’s US invoicing is live and free: US dollars, routing and account numbers on the invoice, PDF export, no subscription. Start invoicing free on the US page.

Carearoo drafts the Medicare progress report and the evaluation and plan of care for US clinicians from the federal rules quoted on this page; both are live from the US page, and your first report is free. The point of it is the one this page makes: a draft that carries the certification date, the progress-report period and the justification sentence in the places a reviewer looks, so the KX attestation is true before the claim goes out. Not a faster note. A note that holds up.

Two related pages for the rest of the record: the FCE report guide for functional capacity evaluations, and the school-based evaluation report guide for IDEA evaluations, which sit outside Medicare Part B and outside this threshold.

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