SNF PDPM Billing: MDS 3.0, Consolidated Billing, and Part A/B Split

Skilled nursing facility billing combines clinical assessment, federal eligibility rules, and one of the most distinctive Medicare payment systems in healthcare. Under the Patient-Driven Payment Model (PDPM), payment depends on accurate MDS 3.0 responses, on documented qualifying hospital stays, on consolidated billing of nearly every service the resident receives, and on a clean transition from Part A skilled coverage to Part B outpatient billing. Each of these areas has unforgiving compliance rules. This guide walks through the components and the operational practices that keep SNF revenue cycles healthy.

How PDPM works

PDPM took effect October 1, 2019, replacing the therapy-utilization-driven RUG-IV model with a clinically driven model. PDPM has five case-mix components, each independently rate-adjusted:

1. PT (Physical Therapy): Driven by clinical category and functional status.
2. OT (Occupational Therapy): Same drivers, separate weighting.
3. SLP (Speech Language Pathology): Driven by clinical category, presence of swallowing disorder or mechanically altered diet, and SLP-related comorbidities.
4. Nursing: Driven by clinical extensive services, special care, and functional impairment.
5. NTA (Non-Therapy Ancillary): Driven by qualifying conditions and services like IV medications, infections, and specific procedures.

Each component generates its own per diem rate, and the rates change over the stay. PT and OT rates decrease after day 20 (variable per diem adjustment factor). NTA rates are higher for the first 3 days and decline thereafter. The full per diem is the sum of the five components for that day, multiplied by the wage index and any urban/rural adjustment.

The 3-day qualifying hospital stay

Medicare Part A SNF coverage requires that the resident have an inpatient acute care hospital stay of at least 3 consecutive days within the 30 days before SNF admission. Two operational details cause most denials in this area:

• Observation status does not count. A patient in the hospital for 5 days under observation, then admitted for 1 day, has a 1-day inpatient stay and does not qualify.
• The discharge day does not count. Counting is days of admission and intermediate days, not the discharge day. A patient admitted Monday, discharged Wednesday, has a 2-day stay.

SNFs must verify the qualifying stay before admitting under Part A. Hospital discharge summaries showing dates of service and admission status (inpatient versus observation) are the primary verification document. Many Medicare Advantage plans waive the 3-day rule contractually; SNFs must verify plan-by-plan.

MDS 3.0: the engine of PDPM

The Minimum Data Set (MDS) 3.0 is the standardized comprehensive assessment for SNF residents. It drives PDPM payment, quality reporting, and Five-Star Quality Rating. The 5-Day MDS (Assessment Reference Date within day 1-8 of Part A stay) is the primary payment-driving assessment under PDPM.

High-impact MDS sections for PDPM

• Section A: Identification and admission information, drives payment start date.
• Section GG: Functional Abilities and Goals, drives PT, OT, and nursing case-mix.
• Section I: Active diagnoses, drives PDPM clinical category and NTA comorbidities.
• Section J: Health conditions, including pain and shortness of breath, can affect case-mix.
• Section K: Swallowing/Nutritional Status, drives SLP case-mix.
• Section O: Special Treatments, Procedures, and Programs, drives nursing and NTA components.

MDS coordinators carry a heavy responsibility. Errors in Section GG (functional scoring), Section I (diagnoses), or Section O (special treatments) can shift the resident from one PDPM group to another, costing hundreds of dollars per day across a 30+ day stay. Facilities should run MDS triple checks: clinician completion, MDS coordinator review, and pre-submission audit.

Interim Payment Assessments (IPAs)

Under PDPM, the 5-Day assessment establishes the case-mix groups for the entire stay unless an Interim Payment Assessment (IPA) is completed. An IPA is optional and triggered when significant clinical change occurs and the facility expects a meaningful payment adjustment. IPAs reset the variable per diem schedule, so timing matters and should be modeled before submission.

Consolidated billing: what the SNF must bill

SNF consolidated billing requires that almost every service provided to a Part A resident be billed by the SNF, regardless of who delivers it. Outside providers (radiology groups, lab companies, therapy providers, ambulance services) cannot bill Medicare directly for Part A SNF residents. They must arrange to bill the SNF, and the SNF bills Medicare on the resident's UB-04 claim.

Excluded services (billable separately by outside providers)

The CMS exclusion list is narrow but important. Common excluded services:

• Cardiac catheterization.
• Computed tomography (CT) and magnetic resonance imaging (MRI).
• Radiation therapy.
• Specific chemotherapy administration codes.
• Emergency department services.
• Certain ambulance services for transport to and from excluded services.

The full exclusion list is published annually by CMS and updated on the SNF consolidated billing webpage. Outside providers verify resident SNF Part A status before billing Medicare directly; many providers query the Common Working File before claim submission to confirm.

The Part A to Part B transition

Medicare Part A SNF coverage ends when one of the following occurs:

• The resident no longer requires daily skilled nursing or rehabilitative services.
• The resident exhausts the 100-day benefit period.
• The resident is discharged from the SNF.

When Part A ends but the resident remains in the facility, billing transitions to Part B for ongoing therapy and certain services. Part B billing has its own rules, including the 8-minute rule for timed therapy codes, the KX modifier for therapy threshold exceptions, and MPPR (Multiple Procedure Payment Reduction).

Operational transition checklist

1. Discharge MDS or Part A discharge MDS (depending on circumstances) completed within required timelines.
2. Provider notification: Therapy, lab, and radiology providers updated on resident's payer status.
3. UB-04 final Part A claim cut at the correct date.
4. Part B billing begins, often using CMS-1500 for professional services and UB-04 for facility services depending on context.
5. Resident or family notification of any private pay or Medicaid responsibility for room and board after Part A ends.

HIPPS code accuracy

Under PDPM, the HIPPS code on the SNF claim is generated from the MDS by the grouper. SNFs should never manually edit HIPPS to a different value than the grouper outputs. If clinical reality differs from the MDS-generated HIPPS, the corrective action is to amend the MDS (when justified) or complete an IPA (when clinically appropriate), not to bill a different HIPPS.

HIPPS audits by MACs and recovery auditors compare the billed HIPPS to the MDS as submitted to CMS. Mismatches trigger recoupment. Facilities should run claim-MDS reconciliation reports monthly.

Common SNF denial causes

• 3-day qualifying stay not documented or not met.
• MDS late or incomplete, triggering default payment.
• HIPPS-MDS mismatch on claim.
• Consolidated billing violations by outside providers.
• Skilled care no longer documented but Part A continued.
• Section GG functional scores inconsistent with clinical documentation.

The Bottom Line

SNF billing under PDPM rewards clinical-billing alignment. Accurate MDS responses, well-documented qualifying stays, disciplined consolidated billing oversight, and a clean Part A to Part B transition are the four operational pillars of healthy SNF revenue. Facilities that invest in MDS coordinator training, clinical documentation improvement, and routine pre-bill audits collect at the top of the curve. Facilities that treat MDS as a compliance afterthought leave revenue on the table and accumulate audit exposure.

Related: SNF Billing Services · Home Health PDGM Billing · PT Billing Guide