PDPM Coding Errors That Cost SNFs Thousands in Lost Reimbursement

There is a category of revenue loss in skilled nursing facility billing that does not appear anywhere in a denial report, an AR aging analysis, or a cash flow summary. Claims are submitted. Claims are paid. The revenue arrives on schedule. And the facility is still losing thousands of dollars per month because the PDPM coding behind those claims is systematically lower than the clinical record would support.

PDPM under coding is silent revenue loss. It generates no denial, triggers no audit flag visible to the billing team, and produces no AR aging problem. It simply results in a daily reimbursement rate that is lower than the clinical complexity of the resident population warrants every Part A Day, every billing cycle, indefinitely until someone conducts a PDPM case-mix audit and identifies the pattern.

At MCA Medical Billing Solutions, L.L.C. PDPM case-mix audits on new client facilities consistently identify correctable coding gaps that have been suppressing Medicare reimbursement for months or years. The errors are not random. They cluster in predictable categories that reflect specific weaknesses in how PDPM coding is managed. This post covers those categories, what the errors look like in practice, and what the revenue consequence of each looks like at a facility level.

Error 1: Primary Diagnosis Codes That Map to the Wrong Clinical Category

The primary diagnosis code on the Medicare Part A claim and in Section I of the MDS determines which PDPM clinical category the resident falls into for the PT and OT components. CMS publishes a PDPM ICD-10 mapping table that assigns each ICD-10-CM code to one of ten clinical categories, each carrying a different base payment rate for PT and OT. The category assignment is mechanical the code either maps to a specific category or it does not.

The coding error that costs the most money in this area is selecting a primary diagnosis code that maps to a lower-paying clinical category or to the non-case-mix (Non-CC) category, which generates the lowest possible PT and OT component rates when the clinical record would support a more specific code that maps to a higher-paying category.

A resident admitted following a hip fracture with open reduction internal fixation surgery has a clinical picture that should map to the Major Joint Replacement or Spinal Surgery clinical category one of the higher-paying PDPM categories. If the primary diagnosis is coded as a generic musculoskeletal condition code that maps to a lower category, or if the surgical procedure is not captured in the most specific ICD-10-CM code that reflects the ORIF, the PT and OT component rates for the entire stay are lower than the clinical record supports.

The revenue impact compounds across the stay. At a daily PT and OT component rate difference of twenty to forty dollars between the correct and incorrect clinical category a range that reflects typical category tier gaps a 30-day stay generates between $600 and $1,200 in lost reimbursement on that single coding decision. Applied across multiple residents with similar coding gaps, the monthly revenue impact reaches into the thousands.

What this means for your facility: Every primary diagnosis code used for PDPM billing should be reviewed against the CMS PDPM mapping table before the assessment is locked. The review question is not whether the code is clinically accurate it is whether it maps to the most specific category the clinical record supports. These are different questions, and the second one is the billing question.

Error 2: Nursing Component Under coding

The Nursing component carries the largest payment weight for most long-stay Medicare Part A residents and is the most consistently under coded PDPM element in the SNF setting. The gap between the Nursing component rates that facilities are billing and the rates their residents’ clinical complexity would support is, in many facilities, the single largest correctable revenue gap in the PDPM billing process.

The Nursing component is determined by a combination of clinical conditions, treatments, and care needs documented in the MDS. The specific drivers include active infections with specific comorbidity classifications, IV medication administration requiring clinical monitoring, tracheostomy care, ventilator or respiratory therapy dependence, depression diagnosis with active treatment, stage three and four pressure ulcers, and a range of other nursing-intensive clinical situations. Each qualifying condition or treatment advances the Nursing component to a higher classification tier, and each tier carries a higher daily payment rate.

The under-coding pattern that appears most consistently in PDPM case-mix audits is nursing-intensive conditions that are present in the clinical record documented in nursing notes, present in physician orders, reflected in the medication administration record but absent from the corresponding MDS sections. An IV antibiotic course documented in the MAR that is not coded in Section N. A sepsis diagnosis actively managed with physician orders that is not coded in Section I with the appropriate comorbidity status. A depression diagnosis with active antidepressant therapy in the medication record that is not captured in Section I.

Each missed Nursing component trigger reduces the daily rate by a specific amount that depends on the tier difference. A single qualifying condition that moves the Nursing classification from tier 2 to tier 3 may add fifteen to twenty-five dollars per day in Nursing component payment. Over a 30-day Part A stay, that single missed coding decision represents $450 to $750 in lost reimbursement. For a facility with consistent Nursing component under coding across its Part A population, the monthly revenue gap is significant, and it has been accumulating since the last time anyone specifically audited the Nursing component coding.

What this means for your facility: Nursing component under coding is the highest-value, most correctable PDPM revenue gap at most skilled nursing facilities. A systematic review of the Nursing component trigger list against the current MAR, physician orders, and nursing documentation for every five-day assessment is the most direct way to identify and close this gap.

Error 3: NTA Point Table Gaps

The Non-Therapy Ancillary component calculates payment from a point-based comorbidity score each qualifying condition and medication carries a specific point value, and the sum of points determines the NTA classification tier. The NTA component is particularly impactful in the first three days of a Medicare Part A stay, when CMS applies a higher NTA rate to reflect the front-loaded resource intensity of post-acute admissions.

The NTA coding error that generates the most consistent revenue loss is incomplete secondary diagnosis and medication capture in the MDS. The NTA point table includes specific conditions multiple sclerosis, end-stage renal disease, respiratory failure, septicaemia, chemotherapy administration, specific wound stages and specific medications IV antibiotics, parenteral nutrition, certain specialty drugs that each carry defined point values. When qualifying conditions are present in the clinical record but absent from the MDS, the NTA score is lower than the resident’s actual clinical complexity supports, and every Part A Day bills at a lower NTA rate.

The compounding effect is most significant for the first three days. A resident admitted with IV antibiotic therapy and one or two additional NTA-qualifying comorbidities may have an NTA score that qualifies for a materially higher payment tier than what the MDS captures. At the first-three-day high rate, the daily payment difference between correctly coded and under coded NTA can be twenty to forty dollars or more per day. Three days of that difference is $60 to $120 in lost revenue from a single component in a single admission and the pattern repeats with every new admission where the NTA review is not conducted systematically.

The systematic fix is a structured NTA coding review as part of the five-day assessment process specifically cross-referencing the NTA point table against the current physician orders, MAR, and active diagnoses before the assessment is locked. This review identifies both the conditions that should be coded and the conditions that are coded without documentation support, protecting the facility on both the revenue and the compliance side of the PDPM coding equation.

What this means for your facility: The NTA high-rate period for days one through three of every new Part A admission is a billing opportunity that compounds across your admission volume. If the NTA review is not a structured step in your five-day assessment process, the first three days of every new Medicare admission may be paying at a lower NTA rate than the clinical record supports.

Error 4: Section GG Functional Score Optimism

The functional score derived from Section GG of the MDS affects PDPM payment rates across the PT, OT, and SLP components. The functional score tier low, medium, or high impairment is determined by the resident’s rated ability in specific self-care and mobility activities. Higher impairment generates higher functional component payment. Lower impairment generates lower payment.

The Section GG error that consistently suppresses PDPM payment is optimistic scoring – scoring the resident’s functional ability based on what they can do at their best, or what therapy goals project they will achieve, rather than what they demonstrated during the assessment reference period. This error is not usually intentional. It reflects a clinical documentation culture that defaults to optimistic functional descriptions appropriate for motivational care planning but inaccurate for PDPM functional scoring.

The revenue consequence of optimistic Section GG scoring is a functional impairment tier that understates actual impairment placing residents in the low or medium tier when their observed function during the assessment period would support the medium or high tier. The daily rate difference between functional impairment tiers is component-specific and varies by clinical category but can range from ten to thirty dollars per day across the PT, OT, and SLP components combined. At a median difference of fifteen dollars per day across all affected residents in a 100-bed facility with a 20% Medicare Part A census, the monthly revenue impact of systematic Section GG optimism approaches thousands of dollars.

What this means for your facility: Section GG scoring discipline is a revenue management function. The question the scoring should answer is not what the resident can do it is what they did, and what level of assistance they required, during the assessment reference period. A brief documentation notes from the clinical observer confirming the basis for the score provides both the accuracy and the audit support.

Error 5: SLP Component Coding Gaps

The Speech-Language Pathology component is frequently the most under optimized of the five PDPM components not because it is less important, but because its payment drivers are less intuitively connected to the typical post-acute admission reason than the therapy and nursing components.

The SLP component is driven by cognitive status scores from Section C, swallowing disorder documentation, mechanically altered diet or thickened liquid requirements from Section K, and specific SLP-relevant diagnoses including aphasia, laryngectomy, and other communication and swallowing disorders. Residents with cognitive impairment and swallowing disorders receive significantly higher SLP component rates than residents without these characteristics but only when the characteristics are captured with the required specificity in the MDS.

The coding gap that most commonly suppresses SLP payment is swallowing disorder documentation that is present in therapy evaluations but not specifically coded in the MDS. A speech therapy evaluation that documents dysphagia requiring thickened liquids and a mechanically altered diet is clinically clear but if the corresponding MDS items in Section K are not completed with the specific codes that reflect those diet modifications and the swallowing disorder, the SLP component does not capture the full payment weight the clinical picture supports.

Similarly, residents whose cognitive impairment is documented by nursing staff confusion, disorientation, poor safety awareness but whose Section C BIMS score does not reflect the documented impairment generate lower SLP component rates than the clinical documentation would support. The BIMS is an administered assessment, not a nurse’s observation score, but when the administered assessment result is inconsistent with the nursing documentation of cognitive function, a review of both is warranted.

What this means for your facility: For every new Medicare admission with a speech therapy evaluation, the MDS Section K items should be reviewed against the evaluation findings before the five-day assessment is locked. If the therapy evaluation documents a swallowing disorder with diet modifications, those modifications should appear specifically in Section K not just in the therapy documentation.

Quantifying the Revenue Impact at Your Facility

The revenue impact of PDPM coding errors is facility-specific it depends on the clinical complexity of the resident population, the current coding practices, and how long the errors have been accumulating. For a 100-bed facility with a typical Medicare Part A census of 15 to 20 residents and a 30-day average Part A length of stay, a combination of Nursing component under coding and primary diagnosis mapping errors can represent $5,000 to $15,000 or more per month in lost reimbursement that the facility is entitled to but not capturing.

The only way to quantify the gap accurately for your facility is a PDPM case-mix audit comparing actual HIPPS code distributions and component coding against the clinical record for a representative sample of Part A residents. That audit produces a specific estimate of the revenue opportunity and identifies the exact coding gaps that, once corrected, will begin capturing that revenue in future billing cycles.

How MCA Medical Billing Solutions L.L.C. Identifies and Closes PDPM Coding Gaps

MCA Medical Billing Solutions, L.L.C. conducts PDPM coding validation as part of our standard SNF billing management reviewing primary diagnosis mapping, Nursing and NTA component coding, Section GG scoring accuracy, and SLP component drivers before every five-day assessment is locked. For new client facilities, we conduct a PDPM case-mix audit as part of onboarding to quantify the existing revenue gap and establish the corrective coding practices that will capture it going forward.

If your facility has not had a PDPM case-mix audit in the past six months, the audit itself may be the most valuable billing review you have not done. Contact MCA Medical Billing Solutions L.L.C. for a free assessment.