SNF PPS: Patient-Driven Payment Model (PDPM) for Skilled Nursing Facilities

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The Skilled Nursing Facility PPS pays a per diem rate for each day of a covered stay, as set under the Patient-Driven Payment Model (PDPM). PDPM classifies each patient across five case-mix components plus a non-case-mix component, and adjusts three of those components by day of stay. This guide breaks down why SNF payments are under PDPM, the case-mix components that drive the rate, how the per diem is built, and the role of the MDS assessment.

🔄 From RUG-IV to PDPM (why it changed)

For years, SNF PPS classified patients under RUG-IV (Resource Utilization Groups), a model that tied much of the payment to the volume of therapy minutes delivered. The RUG-IV model unintentionally created an incentive to provide therapy based on payment thresholds rather than patient need. Effective October 1, 2019, CMS replaced RUG-IV with the Patient-Driven Payment Model (PDPM). This program was intended to base payment on the patient's clinical characteristics and care needs, instead of therapy volume. Under PDPM, the diagnoses and conditions documented for the patient drive classification, not the minutes of therapy logged. This information then drives the case-mix classification and the resulting per diem. The PDPM change cut administrative load as well. PDPM eliminated the scheduled 14-, 30-, 60- and 90-day PPS assessments and the therapy-driven OMRAs (Start of Therapy, End of Therapy, and Change of Therapy), leaving a much lighter assessment schedule for practitioners.

🧩 The five case-mix components (PT, OT, SLP, Nursing, NTA)

PDPM evaluates each patient across five separate case-mix components, each classified and weighted independently:

• PT (Physical Therapy): classified by the patient's primary reason for the SNF stay, mapped to one of four collapsed clinical categories, combined with a function score drawn from Section GG of the MDS.

• OT (Occupational Therapy): the same four clinical categories and the same function score as PT.

• SLP (Speech-Language Pathology): driven by the presence of an acute neurologic condition, SLP-related comorbidities, cognitive impairment, a swallowing disorder, and use of a mechanically altered diet.

• NTA (Non-Therapy Ancillary): captures the cost of non-therapy services such as drugs and supplies. NTA is scored from a list of 50 qualifying comorbidities and conditions, each worth 1 to 8 points based on relative cost.

• Nursing: reflects nursing care needs, including clinical conditions and functional status.
  

Each component places the patient into a group with its own case-mix index. The five component payments are then combined and added to a flat non-case-mix component that covers room, board, and other costs that don't vary by patient acuity. Residents with HIV/AIDS receive two targeted adjustments: the maximum 8 points in the NTA component, and an 18% add-on to the nursing component. 📅 Per Diem Rates And The Variable Per Diem Adjustment

PDPM pays a per-diem (per-day) rate, not a single per-stay amount. Each component's case-mix index is multiplied by its unadjusted federal per-diem base rate. The PT, OT, and NTA results are then multiplied by a day-specific variable per-diem factor. The five case-mix components and the non-case-mix component are summed, and the labor-related share of that total is adjusted by the wage index for the facility's CBSA. A defining feature of PDPM is the variable per diem adjustment, which reflects how resource use changes over a stay. It applies to three of the five components:

• NTA pays triple the case-mix adjusted rate on days 1 through 3, then the standard rate from day 4 onward.

• PT and OT pay the full rate for days 1 through 20, then decline by two percentage points every seven days.

• SLP and Nursing are not day-adjusted.
  

Under the interrupted stay policy, the variable per-diem counter does not reset. If a resident is discharged and readmitted within the three-day interruption window, the stay is treated as continuous, and the schedule picks up where it left off. CMS updates the federal per diem base rates every fiscal year through the SNF market basket and productivity adjustments. The case-mix indexes are not updated annually: they were set when PDPM took effect and have been recalibrated once, through the parity adjustment phased in over FY2023 and FY2024. What changes most years is the ICD-10 mapping that drives clinical-category assignment. One further caveat: the wage-adjusted rate is not the final payment. The SNF Value-Based Purchasing program withholds 2% of Part A fee-for-service payments and redistributes a portion as incentive payments, and facilities that fail to report SNF Quality Reporting Program data lose 2 percentage points off the annual update. 🗂️ MDS (Minimum Data Set) Assessment

PDPM classification comes from the MDS (Minimum Data Set), the standardized resident assessment used in Medicare and Medicaid certified nursing facilities. For payment purposes, a 5-day PPS assessment is required for every covered Medicare Part A stay. The assessment drives the classification for the entire stay unless an optional Interim Payment Assessment is completed after a significant clinical change. A Part A PPS Discharge Assessment is also required, though this does not affect payment. The MDS captures the diagnoses, cognitive and functional status, and clinical conditions that feed each of the five case-mix components. Because the MDS data determines the component classifications, accurate and complete MDS coding directly affects the per-diem payment.

💰 Pricing SNF claims accurately

Because CMS updates the base rates every fiscal year and revises the ICD-10 mappings most years, keeping SNF pricing accurate is an ongoing effort. It can be difficult for processing teams to keep patient-driven payment models accurate. SNF PRICERActive™ maintains the current PDPM components, rates, and adjustments so each claim prices against the correct methodology. See how Micro-Dyn prices SNF alongside IPPS, OPPS/APC, ASC, IRF, HH, IPF, and ESRD. Learn how SNF PPS fits into the broader Medicare payment landscape in our pillar guide, What Is a Prospective Payment System?. For a related post-acute setting, see Understanding IRF-PPS reimbursement.