Medicare Part B for SLPs: Thresholds, the KX Modifier & Plans of Care

Medicare Part B pays for outpatient speech-language pathology — in clinics, private practice, home health under certain conditions, and Part B stays in skilled nursing facilities. It also sets the rules that most commercial payers copy. If you understand Part B, you understand eighty percent of medical billing in this field.

Coverage basics

Part B covers medically necessary, skilled speech-language pathology services delivered under a plan of care that a physician or non-physician practitioner certifies. Three things must be true and documented:

• The service requires the knowledge and judgment of a qualified SLP.
• The service is reasonable and necessary for the patient's diagnosis and condition.
• The amount, frequency, and duration are reasonable for that patient.

Note what is not required: continued measurable improvement. Since the Jimmo settlement, maintenance therapy is covered when the skill of a therapist is needed to maintain function or slow decline. Documenting "plateaued, discharge" out of reflex leaves legitimate coverage on the table — but the note must show why an SLP, not a caregiver, was needed.

The plan of care and certification

The plan of care must include, at minimum:

• Diagnoses (medical and treating)
• Long-term treatment goals
• Type, amount, duration, and frequency of therapy services

It must be certified by a physician or NPP, generally within 30 days of the initial evaluation, and recertified when the plan is significantly modified or when the certified duration ends. Treatment can begin before the signature comes back as long as you obtain it timely — but unsigned plans of care are one of the most common audit takebacks.

Progress reporting

Medicare requires a progress report at least once every 10 treatment days. It must compare current objective status to baseline, state goal progress, and justify continued skilled care. It can be embedded in a daily note as long as all required elements appear. Missing progress reports invalidate the intervening visits, not just the report.

The therapy threshold and the KX modifier

The old hard therapy cap is gone. What remains is an annual dollar threshold, indexed yearly, that combines speech-language pathology and physical therapy into a single shared amount (occupational therapy has its own). Once a patient's combined SLP + PT charges exceed that threshold for the calendar year:

• Append the KX modifier to each claim line, attesting that services are medically necessary and that the justification is in the medical record.
• Above a second, higher threshold, claims are subject to targeted medical review. You do not have to do anything different at that point except be genuinely defensible.

The KX modifier is an attestation, not a magic key. Applying it without documentation that explains why the patient still needs skilled care is a compliance problem. Both dollar thresholds change every January — verify the current figures with your MAC or ASHA rather than relying on last year's numbers.

Required modifiers

• GN on every SLP service line — always, threshold or not.
• KX above the annual threshold.
• 59 / X{EPSU} to unbundle legitimately distinct services flagged by NCCI edits.
• GA when an ABN is on file for a service likely to be denied.

The ABN

The Advance Beneficiary Notice tells a patient in advance that Medicare probably will not pay and that they may be responsible. Issue it before the service, explain it, and get it signed. You cannot bill the patient for a denied non-covered service without one. Do not issue blanket ABNs to every patient at intake — routine ABNs are themselves a violation.

Other Part B mechanics

• 8-minute rule applies only to your timed codes (97129/97130, 96105, 96125, 92607/92608). Most SLP codes are untimed, one unit per session.
• Therapy assistants: Medicare does not recognize speech-language pathology assistants for Part B billing the way it recognizes PTAs and OTAs. Services must be furnished by the SLP.
• Students: Part B allows billing for services furnished by a student only when the qualified SLP is in the room, directing the service, and not engaged with anyone else. Rules differ by setting.
• Group therapy (92508) is billed per patient and requires documentation of the group's composition and each patient's individualized goals.
• Telehealth coverage for SLP services has shifted repeatedly since 2020 and is periodically extended by statute. Confirm the current status before scheduling.

Where claims go wrong

1. Missing or late plan-of-care certification.
2. No progress report within 10 treatment days.
3. KX applied without supporting justification in the note.
4. Wrong therapy discipline modifier (GP instead of GN).
5. Notes describing activities instead of skilled service — see the SOAP note guide.
6. Diagnosis code that does not support medical necessity for the CPT billed.

When a claim is denied anyway, the appeal process has five formal levels — start with the denial and appeals guide.

Medicare rules, thresholds, and telehealth provisions change annually and by statute. Verify current requirements with your Medicare Administrative Contractor and ASHA before billing.