The Medicare KX modifier and the therapy threshold, in CMS’s words
The Bipartisan Budget Act of 2018 ended the Medicare outpatient therapy caps but kept the old cap amounts as a threshold. Above it, claims must carry the KX modifier to confirm that the therapy is medically necessary and documented. CMS sets one threshold for physical therapy and speech-language pathology combined and a separate one for occupational therapy. CMS publishes the amounts for each calendar year on its Therapy Services page, and they change every year. This page does not copy them; check the CMS page for the current year.
Quoted from official pages checked November 10, 2026. Confirm current requirements, fees, and dates on those sites. This page is not legal advice and does not guarantee eligibility, certification, or licensure.
Sources read on November 10, 2026: CMS’s Therapy Services page (page last modified 03/10/2026), section ‘Implementation of the Bipartisan Budget Act of 2018’; the Medicare Claims Processing Manual, Chapter 5 – Part B Outpatient Rehabilitation and CORF/OPT Services (PDF), sections 10.2 and 10.3.3 (Rev. 4214); and the Medicare Benefit Policy Manual, Chapter 15 (PDF), section 220.2. No threshold amounts, review amounts, or payment amounts are copied.
What the threshold is
CMS’s Therapy Services page states: “Through section 50202 of the BBA of 2018, the law preserves the former therapy cap amounts as thresholds above which claims must include the KX modifier as a confirmation that services are medically necessary as justified by appropriate documentation in the medical record.” It continues: “Just as with the incurred expenses for the therapy cap amounts, there is one amount for PT and SLP services combined and a separate amount for OT services. This amount is indexed annually by the Medicare Economic Index (MEI).”
Chapter 5, section 10.2, says the law “retains the former cap amounts as a threshold of incurred expenses above which claims must include a modifier as a confirmation that services are medically necessary as justified by appropriate documentation in the medical record. This is termed the KX modifier threshold.”
What the KX modifier means now
Section 10.3.3 states: “Effective for dates of service on or after January 1, 2018, the KX modifier continues to be used. It no longer represents an exception request but serves as a confirmation that services are medically necessary after the beneficiary has exceeded the KX modifier threshold of incurred expenses.”
It lists what the provider attests to: “By appending the KX modifier, 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.” That last item, like much of section 10.3.3, still uses the older cap-and-exception wording; it is left as CMS wrote it.
When CMS says to use it
The section states: “The KX modifier shall not be added to any line of service that is not a medically necessary service”. It also says: “In addition to the KX modifier, the GN, GP and GO modifiers shall continue to be used.”
For professional claims: “it is only appropriate to append the KX modifier to a service that reasonably may exceed the cap.” And: “Use of the KX modifier when there is no indication that the cap is likely to be exceeded is abusive.”
For institutional claims: “When the cap is exceeded by at least one line on the claim, use the KX modifier on all of the lines on that institutional claim that refer to the same therapy cap (PT/SLP or OT), regardless of whether the other services exceed the cap.”
Claims without it
CMS’s Therapy Services page states: “Claims for services over the KX modifier threshold amounts without the KX modifier are denied.” Section 10.3.3 adds: “In cases where appending the KX modifier would have been appropriate, contractors may reopen and/or adjust the claim, if it is brought to their attention.” Appeals are on Medicare appeals.
Targeted medical review
The Therapy Services page says the law also keeps a targeted medical review process with its own threshold amount, which CMS publishes; that amount is not copied here either. CMS states: “The targeted MR process means that not all claims exceeding the MR threshold amount are subject to review as they once were.”
Liability and the ABN
Chapter 15, section 220.2, states: “Under section §1833(g)(8), the therapist or therapy provider is financially liable for the cost of therapy services provided to a beneficiary above the threshold amount when Medicare denies payment for failure to use the KX modifier to indicate that the services are medically necessary as justified by documentation in the medical record.” It continues: “In order for the therapist or therapy provider to transfer liability to the beneficiary, s/he must issue a valid ABN, Form CMS-R-131.” See the Medicare ABN.
The documentation the attestation points to is in Chapter 15, sections 220.2 and 220.3; see Medicare therapy plans of care and Medicare progress reports.
What this page does not do
It does not copy any KX threshold, medical review threshold, payment amount, or coinsurance figure, and does not say whether any claim needs the modifier. It is not legal, billing, or compliance advice. Confirm current rules with the agency or organization that publishes them, your employer, and your state board.