Chronic Kidney Disease HCC Coding Guide
Chronic Kidney Disease (e.g. N18.5) maps to HCC 326 (Chronic Kidney Disease, Stage 5) under the CMS-HCC V28 risk adjustment model, with a community, non-dual, aged RAF weight of 0.815; V28 reached 100% phase-in for payment year 2026. N18.1, chronic kidney disease, stage 1, is non-HCC under V28. It can also map to HCC 327 (Chronic Kidney Disease, Severe (Stage 4)) and HCC 329 (Chronic Kidney Disease, Moderate (Stage 3, Except 3B)) when the documentation supports those manifestations.
Complete HCC coding guide for Chronic Kidney Disease (CKD) N18.x including ICD-10 to HCC mapping, V28 RAF weights, and documentation requirements.
Medically reviewed by Jess P., CPC · Reviewed: May 10, 2026 · Updated for CMS-HCC V28 and FY2026 ICD-10-CM
Quick Facts
HCC Categories
HCC 326, Chronic Kidney Disease, Stage 5
HCC 327, Chronic Kidney Disease, Severe (Stage 4)
HCC 329, Chronic Kidney Disease, Moderate (Stage 3, Except 3B)
HCC 328, Chronic Kidney Disease, Moderate (Stage 3B)
RAF Weight Range
0.127 to 0.815
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
6 ICD-10 codes map to payment HCCs
What HCC category does Chronic Kidney Disease map to under V28?
Chronic kidney disease is a progressive condition affecting roughly 37 million US adults and is a meaningful driver of HCC risk adjustment scores. Under CMS-HCC V28, CKD maps to payment HCCs across a wider range of severity than coders often expect. Stage 5 falls in HCC 326 (community non-dual aged RAF about 0.815), severe stage 4 in HCC 327 (about 0.514), stage 3B in HCC 328 and the rest of stage 3 in HCC 329 (each about 0.127). Document the CKD stage from the most recent GFR, the underlying etiology, and any dialysis or functioning transplant status. The 3a versus 3B split matters in V28 because 3B routes to its own HCC, so specify it whenever the GFR supports it.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| N18.4 | Chronic kidney disease, stage 4 (severe) | Yes | HCC 327 |
| N18.5 | Chronic kidney disease, stage 5 | Yes | HCC 326 |
| N18.6 | End stage renal disease | Yes | HCC 326 |
| N18.30 | Chronic kidney disease, stage 3 unspecified | Yes | HCC 329 |
| N18.31 | Chronic kidney disease, stage 3a | Yes | HCC 329 |
| N18.32 | Chronic kidney disease, stage 3b | Yes | HCC 328 |
| N18.1 | Chronic kidney disease, stage 1 | Yes | No HCC (not risk-adjusting under V28) |
| N18.2 | Chronic kidney disease, stage 2 (mild) | Yes | No HCC (not risk-adjusting under V28) |
| N18.9 | Chronic kidney disease, unspecified | Yes | No HCC (not risk-adjusting under V28) |
| Z99.2 | Dependence on renal dialysis | Yes | No HCC (not risk-adjusting under V28) |
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.
HCC Buddy maps Chronic Kidney Disease from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
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 reorganized CKD into stage-specific HCCs rather than the smaller set of broad categories used in the prior V24 model. Stage 5 now sits in HCC 326, severe stage 4 in HCC 327, stage 3B in HCC 328, and the remainder of stage 3 in HCC 329, each with its own recalibrated RAF weight. The headline change for coders is that moderate CKD (stage 3, including the 3B split) now carries payment value in V28, so the older habit of treating only stages 4 and 5 as worth capturing is outdated. Etiology codes still route to their own categories, a diabetic or hypertensive cause maps to its respective HCC rather than into the CKD category, so document both the stage and the underlying cause to capture the full picture accurately.
Related Conditions
Diabetes Mellitus (Type 2)
HCC 383, HCC 298, HCC 38, HCC 37, RAF 0.646–0.336–0.166–0.166
Heart Failure
HCC 226, HCC 224, HCC 225, RAF 0.360–0.360–0.360
Organ Transplant Status
HCC 276, HCC 221, HCC 35, HCC 62, RAF 2.531–1.053–0.949–0.376
Peripheral Vascular Disease
HCC 263, HCC 383, HCC 264, RAF 1.118–0.646–0.455
Related references
Sources
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.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed May 10, 2026.
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