Chronic Kidney Disease HCC Coding Guide
Complete HCC coding guide for Chronic Kidney Disease (CKD) N18.x including ICD-10 to HCC mapping, V28 RAF weights, and documentation requirements.
Quick Facts
HCC Categories
HCC 329 — Chronic Kidney Disease, Stage 5
HCC 330 — Chronic Kidney Disease, Stage 4
RAF Weight Range
0.289
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026 — 100% phase-in)
3 ICD-10 codes map to payment HCCs
Overview
Chronic kidney disease is a progressive condition affecting approximately 37 million US adults and is a significant driver of HCC risk adjustment scores. Under CMS-HCC V28, CKD stages 4 and 5 map to payment HCCs while earlier stages (1-3) do not. CKD frequently co-occurs with diabetes and hypertension, creating important coding relationships. Coders must document the CKD stage based on GFR values, the underlying etiology, and whether the patient is on dialysis or has a functioning transplant. The distinction between stages 3a and 3b was added in ICD-10-CM to improve clinical specificity, though neither maps to a V28 payment HCC.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| N18.4 | Chronic kidney disease, stage 4 (severe) | Yes | HCC 330 |
| N18.5 | Chronic kidney disease, stage 5 | Yes | HCC 329 |
| N18.6 | End stage renal disease | Yes | HCC 329 |
| N18.30 | Chronic kidney disease, stage 3 unspecified | Yes | No HCC |
| N18.31 | Chronic kidney disease, stage 3a | Yes | No HCC |
| N18.32 | Chronic kidney disease, stage 3b | Yes | No HCC |
| N18.1 | Chronic kidney disease, stage 1 | Yes | No HCC |
| N18.2 | Chronic kidney disease, stage 2 (mild) | Yes | No HCC |
| N18.9 | Chronic kidney disease, unspecified | Yes | No HCC |
| Z99.2 | Dependence on renal dialysis | Yes | Separate HCC |
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS rate announcement for payment calculations.
Documentation Tips
Always document the current CKD stage (1-5) based on the most recent GFR measurement — never code 'unspecified' when a stage is determinable.
Document the underlying cause of CKD (diabetic nephropathy, hypertensive nephrosclerosis, etc.) to capture additional HCC mappings.
When CKD is due to diabetes, use combination code E11.22 in addition to the N18 stage code.
Document dialysis status and modality (hemodialysis vs. peritoneal) when applicable.
Record the most recent eGFR value and date to support the documented CKD stage.
Document whether the patient has a functioning kidney transplant, which requires Z94.0 in addition to the CKD stage.
Note progression or stability of CKD compared to prior encounters to satisfy the 'Monitor' component of MEAT.
For CKD stage 3, specify 3a or 3b based on GFR to use the more specific ICD-10-CM codes.
Common Coding Mistakes
Coding N18.9 (CKD, unspecified) when the medical record contains GFR values that clearly indicate a specific stage.
Failing to code the diabetic etiology (E11.22) alongside the CKD stage when diabetes is the documented cause.
Confusing ESRD (N18.6) with CKD stage 5 (N18.5) — ESRD indicates the patient is on or being considered for renal replacement therapy.
Not updating the CKD stage when labs show progression from stage 3 to stage 4, missing the HCC capture opportunity.
V24 to V28 Changes
V28 introduced new HCC categories 329 and 330 specifically for CKD stages 5 and 4, replacing the broader V24 HCC 137 (Chronic Kidney Disease, Stage 5) and HCC 138 (Chronic Kidney Disease, Severe — Stage 4). The recalibration in V28 maintained CKD 4 and 5 as payment HCCs but adjusted the RAF weights. Importantly, CKD stages 1-3 remain non-payment HCCs in V28, making it critical to document progression to stage 4 when clinically supported.
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