Summary & Overview
HCPCS Level II S9131: Physical Therapy, Home Per Diem
HCPCS Level II code S9131 denotes physical therapy services provided in the home on a per diem basis. This code is used to capture home-based therapy encounters where providers bill a daily rate for skilled physical therapy interventions. Nationally, home-based rehabilitation delivery is a growing component of post-acute and community-based care, and accurate use of per diem home therapy codes affects billing clarity and care coordination.
Key payers examined include Aetna, Blue Cross Blue Shield, Cigna Health, and UnitedHealthcare. Readers will learn how S9131 is defined and applied in clinical billing, the clinical contexts that commonly prompt home physical therapy, and how related therapy codes are used alongside per-diem reporting. The publication also outlines operational considerations for documenting home-based therapy encounters, common ICD-10 conditions that align with home PT services, and crosswalks to time- and procedure-based therapy codes used for reporting specific interventions.
The content provides benchmarks and policy context relevant to payers and providers, notes coding relationships to standard therapy CPT codes, and flags where input data is missing for service-line metadata. Data not available in the input is stated where applicable.
Billing Code Overview
HCPCS Level II code S9131 represents physical therapy provided in the home on a per diem basis. This code describes a miscellaneous, non-facility service line for skilled physical therapy delivered in a home setting where billing is reported as a daily (per diem) charge. The service type is Physical Therapy (HCPCS Level II miscellaneous service). If additional billing details or service-line metadata are required, Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A typical patient is an older adult receiving skilled services at home for mobility and functional limitations following an acute exacerbation of chronic low back pain with associated knee pain and generalized weakness. The home health agency schedules a per diem physical therapy visit billed with HCPCS Level II code S9131 for direct treatment in the home setting. The clinical workflow includes an initial home evaluation by a physical therapist or rehabilitation practitioner to establish a plan of care, implementation of therapeutic exercises, neuromuscular reeducation, and functional task training during the per diem visit, documentation of daily progress and safety assessment, and coordination with the referring physician for updates to the plan of care and any changes in frequency or discipline.
Coding Specifications
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Modifiers listed:
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GN: Services delivered under an outpatient speech-language pathology plan of care — used when the billed per diem home-based service is provided under a speech-language pathology plan of care. -
GO: Services delivered under an outpatient occupational therapy plan of care — used when the billed per diem home-based service is provided under an occupational therapy plan of care. -
Provider taxonomies and specialties: