How PDPM margin is modeled for SNF admissions.
This page explains what PDPM is, how margin is estimated from the per-diem and the cost of care, and what moves it. It is general education only and does not guarantee a financial result.
What PDPM is
The Patient-Driven Payment Model (PDPM) is how Medicare classifies a covered Part A skilled nursing stay for payment; Medicare Advantage plans may reference PDPM-informed rates, but terms vary by contract. Instead of paying primarily on therapy volume, PDPM builds a per-diem rate from a resident's clinical characteristics, grouped into separate case-mix components plus a non-case-mix portion. The formal classification is set by the MDS assessment after admission. Referral documentation only previews it, so a pre-admission estimate is only a starting point to verify.
Case-mix components
PDPM scores physical therapy, occupational therapy, speech-language pathology, nursing, and non-therapy ancillary needs as distinct components, each tied to different clinical and diagnostic details.
Documentation drives classification
Diagnoses, comorbidities, functional status, and clinical notes determine how each component classifies. Missing or unclear source support can change where a stay lands.
The rate can shift over a stay
Some components are designed to change across the length of stay, so timing and expected duration are part of any model.
PDPM sets the payment side
PDPM describes how a stay is classified for payment. By itself it does not tell you what a specific stay will cost to deliver or what it will net.
Margin is estimated reimbursement minus estimated cost of care
A margin model compares two projections, and both sides are estimates. The reimbursement projection follows the per-diem a stay is modeled to classify into under PDPM. The cost projection reflects what delivering that care is expected to require. Because each side depends on documentation and assumptions, the model is only as trustworthy as its inputs, which is why every figure should be reviewed against source records.
Estimated reimbursement = per-diem × expected length of stay.
Estimated cost of care = (routine + therapy + medication cost per day) × length of stay + one-time admission costs.
Estimated margin = estimated reimbursement minus estimated cost of care.
The calculator uses a flat per-diem; real PDPM components change over a stay (PT/OT adjust down after day 20; NTA pays more in the first three days).
Related: PDPM admissions signals, MDS Section GG guide
What drives PDPM margin
Margin moves when either the estimated reimbursement or the estimated cost of a stay moves. On the reimbursement side, that traces back to how well the documentation supports case-mix classification. On the cost side, it traces back to what the stay actually requires to deliver. To model a single admission with your own per-diem, stay length, and costs, use the in-browser PDPM margin calculator.
Clinical complexity and comorbidities
Conditions that inform the non-therapy ancillary and nursing components can change how a stay classifies when they are documented and supported.
Therapy and functional need
Therapy support and functional status, including Section GG items, feed the therapy components and shape both the model and the plan of care.
High-cost medications and supplies
Expensive medications, wound care, isolation, and equipment sit on the cost side of the model and are worth flagging during packet review.
Length and timing of the stay
Because parts of the per-diem are designed to change over a stay, expected duration and timing affect estimated reimbursement as well as accumulated cost.
What AdmitScore does with a referral packet. AdmitScore™ helps admissions staff find the important information in a hospital referral packet, verify it at the source page, and make their own admission decision. It does not calculate margin. The calculator described here is a separate standalone tool.
Questions about rates and the calculator
Where do I find my per-diem rate?
For Medicare Part A stays, your MDS classification (via your rate software) determines the PDPM per-diem; for Medicare Advantage, the contract sets the rate. If you only have a HIPPS code, a PDPM rate calculator converts it to component rates.
Does the PDPM margin calculator send my numbers anywhere?
No. The calculator runs entirely in your browser and never asks for patient information. It takes dollars and days only.