End-stage renal disease (ESRD) is the final, irreversible stage of chronic kidney disease. For nephrology practices, ESRD patients represent the highest billing complexity in the specialty. Monthly capitation payments, dialysis session codes, comorbidity sequencing, and Medicare’s ESRD-specific rules all interact on every claim.
ICD-10 code N18.6 is the foundation of ESRD billing. Every monthly service, every dialysis management claim, and every comorbidity code stack is built on whether N18.6 is correctly selected, sequenced, and documented. When it isn’t, payer scrubbers catch it automatically, before a human ever reviews the claim.
This guide covers the complete N18.6 code framework, including how ESRD interacts with diabetes and hypertension combination codes, CPT code pairings for monthly capitation payments, and sequencing rules. It also explains documentation requirements and common denial patterns that consistently cost nephrology practices revenue.
What Is the ICD-10 Code for ESRD?
The ICD-10-CM code for end-stage renal disease is N18.6. It is a billable, specific code under the chronic kidney disease (CKD) category and became effective in the 2026 ICD-10-CM edition on October 1, 2025.
N18.6 applies when a patient has reached the terminal stage of chronic kidney disease and requires renal replacement therapy, such as hemodialysis or peritoneal dialysis. It may also apply to patients who have received a kidney transplant, depending on their current clinical status and documentation. The clinical threshold for ESRD is a GFR below 15 mL/min/1.73m².
N18.6 is one of the highest-impact codes in nephrology billing. N18.6 determines DRG assignment on inpatient claims and supports hospital payment classification. It also triggers Medicare’s ESRD Prospective Payment System (PPS) for dialysis and establishes medical necessity for Monthly Capitation Payment (MCP) codes used in nephrology practices.
Key Rule: N18.6 always requires additional codes to paint the complete clinical picture. ICD-10-CM instructs coders to add Z99.2 (dependence on renal dialysis) whenever dialysis is part of the treatment plan. Without Z99.2, claims are incomplete and auditable.
The Full ESRD ICD-10 Code Table
This section includes all key ICD-10 ESRD codes used to identify chronic kidney disease stages and end-stage renal disease for accurate clinical documentation and billing purposes.
Primary ESRD and CKD Stage Codes
The following codes represent different stages of chronic kidney disease, and are used based on the patient’s kidney function (GFR level) and dialysis status.
| Code | Description | Billable | Key Requirement |
|---|---|---|---|
| N18.6 | End-stage renal disease | Yes | GFR <15 mL/min; patient on dialysis or transplanted |
| N18.5 | Chronic kidney disease, stage 5 | Yes | GFR <15 mL/min; NOT yet on dialysis |
| N18.4 | Chronic kidney disease, stage 4 (severe) | Yes | GFR 15–29 mL/min |
| N18.3 | Chronic kidney disease, stage 3 (moderate) | Yes — subcodes below | GFR 30–59 mL/min |
| N18.31 | CKD stage 3a | Yes | GFR 45–59 mL/min |
| N18.32 | CKD stage 3b | Yes | GFR 30–44 mL/min |
| N18.2 | Chronic kidney disease, stage 2 (mild) | Yes | GFR 60–89 mL/min |
| N18.1 | Chronic kidney disease, stage 1 | Yes | GFR ≥90 mL/min with kidney damage markers |
| N18.9 | CKD, unspecified | Yes | Use only when stage is not documented |
Companion Codes Always Used with N18.6
These additional codes are commonly paired with N18.6 to capture dialysis status, access care, and treatment monitoring in ESRD patients.
| Code | Description | When to Add |
|---|---|---|
| Z99.2 | Dependence on renal dialysis | Whenever the ESRD patient is on hemodialysis or peritoneal dialysis |
| Z49.01 | Encounter for fitting and adjustment of extracorporeal dialysis catheter | Catheter access management encounters |
| Z49.31 | Encounter for adequacy testing for hemodialysis | Adequacy testing for HD patients |
| Z49.32 | Encounter for adequacy testing for peritoneal dialysis | Adequacy testing for PD patients |
ESRD with Comorbidities: Combination Code Rules
The most complex aspect of ESRD coding is how it interacts with diabetes and hypertension. ICD-10-CM provides specific combination codes for these relationships. Using N18.6 alone when a combination code applies is a coding error and a compliance risk.
ESRD Caused by or Associated with Hypertension
When hypertension is present alongside ESRD, ICD-10-CM requires the use of hypertensive CKD combination codes from the I12 and I13 categories. The combination code replaces the separate coding of hypertension (I10) and ESRD (N18.6). ICD-10-CM assumes a causal relationship between hypertension and CKD unless the physician explicitly documents that the conditions are unrelated.
| Code | Description | When to Use |
|---|---|---|
| I12.0 | Hypertensive CKD with stage 5 CKD or ESRD | Patient has hypertension and ESRD, no heart failure |
| I13.11 | Hypertensive heart and CKD with heart failure and stage 5 CKD or ESRD | Patient has hypertension, heart failure, and ESRD |
| I13.2 | Hypertensive heart and CKD with heart failure and with stage 5 CKD or ESRD | Full triad: hypertension, heart failure, ESRD |
Sequencing Rule for Hypertensive ESRD: The combination code (I12.0 or I13.x) is listed first. N18.6 is then added as a required additional code per the “use additional code” instruction at I12 and I13. Z99.2 follows when the patient is on dialysis.
Example: Hypertensive patient on hemodialysis with ESRD, no heart failure → I12.0, N18.6, Z99.2
ESRD Caused by or Associated with Diabetes
Diabetes mellitus with diabetic CKD is coded using combination codes from the E08–E13 series. When a diabetic patient reaches ESRD, a two-code approach is required: the diabetes combination code first, then N18.6.
| Code | Description | When to Use |
|---|---|---|
| E11.65 | Type 2 diabetes mellitus with hyperglycemia | Combined with N18.6 when diabetes leads to ESRD |
| E11.22 | Type 2 DM with diabetic CKD (stage and type) | Use E11.22 + N18.6 when DM2 is the stated cause of ESRD |
| E10.22 | Type 1 DM with diabetic CKD | Use E10.22 + N18.6 when DM1 is the stated cause of ESRD |
Sequencing Rule for Diabetic ESRD: The diabetes combination code (E11.22 or E10.22) is sequenced first. N18.6 is added as an additional code per the “use additional code” instruction. Z99.2 is added when the patient is on dialysis.
Example: Type 2 diabetic patient on peritoneal dialysis with ESRD → E11.22, N18.6, Z99.2
ESRD with Both Diabetes and Hypertension
When a patient has both diabetes and hypertension contributing to ESRD, both relationships must be coded. ICD-10-CM does not provide a single code that captures all three conditions.
Correct code sequence: E11.22 (or E10.22) → I12.0 → N18.6 → Z99.2
The diabetes code leads because diabetes is typically the primary etiology. If hypertension is documented as the primary cause, I12.0 leads instead. Physician documentation controls sequencing.
N18.6 vs. N18.5: The Most Common Staging Confusion
The single most frequent ESRD coding error in nephrology billing is using N18.5 when N18.6 is correct, or vice versa. The clinical boundary is dialysis initiation — not GFR alone.
| Code | GFR | Dialysis | Clinical Picture |
|---|---|---|---|
| N18.5 | <15 mL/min | No — not yet initiated | CKD stage 5, pre-dialysis; managing conservatively or planning transplant |
| N18.6 | <15 mL/min | Yes — active or kidney transplant received | ESRD; renal replacement therapy is the treatment |
The rule in Plain Terms: The moment a patient begins dialysis, the code changes from N18.5 to N18.6. A patient with a GFR of 8 who is not yet on dialysis is N18.5, not N18.6. A patient with a GFR of 8 who is on hemodialysis three times per week is N18.6.
This distinction matters clinically and financially. N18.5 does not trigger the ESRD Monthly Capitation Payment structure. N18.6 does. Coding N18.5 for an active dialysis patient results in medical necessity failure for MCP codes 90960–90966.
Because a single staging oversight can halt cash flow across an entire patient cohort, partnering with the best nephrology billing services is the most secure way to enforce absolute compliance at the point of charge capture.
What are the Code Sequencing Rules for ESRD Claims?
Code sequencing for ESRD follows different rules depending on the clinical setting and the reason for the encounter. Getting sequencing wrong is among the most common compliance risks in nephrology billing.
Outpatient Sequencing
In outpatient settings, the first-listed diagnosis is the condition chiefly responsible for the encounter. The ICD-10-CM Section IV guidelines govern.
For a routine ESRD dialysis management visit, the encounter reason is the management of ESRD. Sequence as follows:
- If hypertension is the underlying cause: I12.0 first, then N18.6, then Z99.2
- If diabetes is the underlying cause: E11.22 first, then N18.6, then Z99.2
- If neither hypertension nor diabetes: N18.6 first, then Z99.2
- Comorbidities affecting management (e.g., anemia of CKD, D63.1) are added as additional codes
When a Separate, Unrelated Problem is the Reason for the Visit: Code the unrelated condition first, then add N18.6 and Z99.2 as additional codes to reflect the patient’s active chronic condition.
Inpatient Sequencing
The principal diagnosis for inpatient claims is the condition established after study to be chiefly responsible for admission. UHDDS guidelines apply.
If a patient is admitted with a complication of ESRD, such as fluid overload due to missed dialysis, the complication is reported as the principal diagnosis (for example, E87.70). N18.6 is then listed as a secondary diagnosis to indicate the underlying ESRD.
If the patient is admitted for emergent dialysis initiation in a previously undiagnosed ESRD patient, N18.6 is the principal diagnosis.
Accurately sequencing the broader ICD-10 codes for nephrology is critical here; secondary diagnoses like metabolic acidosis (E87.2) or hyperkalemia (E87.5) must be captured to accurately reflect the true clinical resource consumption of the stay.
When N18.6 Is an Additional Diagnosis
N18.6 is appropriately coded as an additional diagnosis (not principal) in three scenarios:
- Admission is for a complication clearly distinct from ESRD (fracture, infection, cardiac event)
- The primary encounter is a procedure with N18.6 coded as the indication for medical necessity
- ESRD is a chronic condition affecting management, but not the chief reason for admission
CPT Codes Paired with ESRD: Monthly Capitation Payments
N18.6 is the required ICD-10 diagnosis code for all Monthly Capitation Payment (MCP) services. The MCP structure governs how nephrologists bill for ESRD management under Medicare. Selecting the wrong CPT code or failing to pair it with N18.6 and Z99.2 produces systematic denials.
Adult ESRD Monthly Services (Age 20 and Older)
The following CPT codes are used for adult ESRD patients based on the number of required face-to-face visits provided each month.
| CPT Code | Description | Required Visits per Month |
|---|---|---|
| 90960 | ESRD-related services, 20+ years, 4+ face-to-face visits | 4 or more |
| 90961 | ESRD-related services, 20+ years, 2–3 face-to-face visits | 2 to 3 |
| 90962 | ESRD-related services, 20+ years, 1 face-to-face visit | 1 |
Pediatric and Adolescent ESRD Monthly Services
Here are CPT codes for pediatric ESRD patients based on age group rather than visit frequency.
| CPT Code | Age Group | Required Visits |
|---|---|---|
| 90963 | Under 2 years | Monthly physician service |
| 90964 | Age 2–11 | Monthly physician service |
| 90965 | Age 12–19 | Monthly physician service |
Home Dialysis Monthly Services
The CPT code below is used for patients receiving home dialysis care, where monthly management is billed under a single service code.
| CPT Code | Description |
|---|---|
| 90966 | ESRD-related services for home dialysis, age 20+, per month |
Dialysis Session Codes (Session-Based Billing)
When a practice opts for session-based billing rather than MCP, these codes apply. Session codes and MCP codes cannot be billed in the same month for the same patient. Use one model consistently.
| CPT Code | Description |
|---|---|
| 90935 | Hemodialysis procedure with physician evaluation |
| 90937 | Hemodialysis requiring repeated physician evaluations |
| 90945 | Dialysis procedure (other than hemodialysis) with one physician evaluation |
E&M Separately Billed with ESRD
A separate E&M visit may be billed when the nephrologist treats a condition entirely unrelated to ESRD management during the same encounter. Modifier 25 must be appended to the E&M code. Routine dialysis-related evaluation cannot be separated from the MCP payment and billed additionally.
What are the Documentation Requirements for N18.6?
Documentation is the first line of defense in an ESRD audit. N18.6 claims are among the highest-scrutiny codes across Medicare and commercial payers. The following documentation must be present at the time of claim submission:
For Every N18.6 Claim
- Explicit diagnosis of end-stage renal disease in the clinical note — not simply “CKD” or “renal failure.”
- GFR value below 15 mL/min/1.73m² documented in labs or referenced by the physician
- Active dialysis modality documented: hemodialysis, peritoneal dialysis, or transplant recipient status.
- Dialysis start date or duration noted in the patient’s history
- If applicable: underlying etiology stated (diabetes, hypertension, glomerulonephritis, etc.)
- Physician’s signature with date of service
For Monthly Capitation Payment Claims (90960–90966)
- Number of face-to-face physician visits during the billing month documented in the chart
- Each visit note must contain a substantive clinical assessment — not just a check-box
- Care coordination activities described (communication with dialysis facility, labs reviewed, treatment plan adjustments)
- Dialysis adequacy parameters documented when applicable (Kt/V, URR)
- Complications or comorbidities managed during the month addressed in the note
- Patient compliance with dialysis schedule noted
For Inpatient ESRD Claims
- Admission history and physical documenting ESRD and dialysis status
- Consultation notes from nephrology when applicable
- Discharge summary must include ESRD as an active diagnosis with dialysis status
- If a complication triggered admission: explicit documentation linking the complication to ESRD or missed dialysis
What are the Medicare Billing Rules for ESRD?
Medicare is the primary payer for the overwhelming majority of ESRD patients. By law, patients with ESRD who are entitled to Medicare benefits receive Medicare as the primary payer regardless of age. This makes ESRD billing compliance a top operational priority for nephrology practices.
The ESRD Prospective Payment System (PPS)
Under the ESRD PPS, Medicare bundles most outpatient dialysis services into a single per-treatment base rate. The rate is adjusted for patient age, comorbidities, and facility location. N18.6 is the required diagnosis to access the ESRD PPS rate.
Drugs administered during dialysis (erythropoiesis-stimulating agents, phosphate binders, and vitamin D analogs) are bundled into the PPS rate and cannot be billed separately to Medicare. Billing them separately is a common compliance error.
MS-DRG Implications for Inpatient ESRD Claims
When ESRD patients are admitted to the hospital, Medicare assigns a Diagnosis-Related Group (DRG) based on the presence and severity of complications or comorbidities.
| DRG | Description | Applies When |
|---|---|---|
| 684 | Renal failure with MCC | N18.6 with major complication or comorbidity |
| 685 | Renal failure with CC | N18.6 with complication or comorbidity |
| 686 | Renal failure without CC/MCC | N18.6 without qualifying complications |
| 698 | Other kidney and urinary tract diagnoses with MCC | N18.6 in context of other kidney diagnoses, with MCC |
Accurate comorbidity coding such as anemia (D63.1), metabolic acidosis (E87.2), hyperkalemia (E87.5), and fluid overload (E87.70) affects DRG assignment and directly impacts inpatient reimbursement. Leaving documented comorbidities uncoded is one of the most common sources of revenue loss in ESRD inpatient billing.
Local Coverage Determinations (LCDs)
Dialysis-related procedures such as vascular access creation, graft revisions, and catheter placements each carry specific LCD requirements. N18.6 must appear as the primary indication diagnosis on these claims. Some MACs require additional supporting codes (e.g., vascular access complication codes) to establish medical necessity. Verifying payer authorization before scheduling vascular access procedures reduces denial risk substantially.
What are the Top ESRD Claim Denial Reasons and Fixes?
Six denial patterns drive the majority of preventable ESRD billing losses across nephrology practices. Each follows a predictable pattern with a clear correction.
Denial 1: N18.5 Coded for an Active Dialysis Patient
A biller codes N18.5 for a patient currently on hemodialysis. The claim fails medical necessity review for the MCP codes submitted.
Fix: Confirm dialysis status before code selection. If the patient is on any form of active renal replacement therapy, the code is N18.6, not N18.5. Conduct a monthly audit of all N18.5 claims in the nephrology practice to identify misclassified active dialysis patients.
Denial 2: Missing Z99.2 on Dialysis Claims
N18.6 is coded correctly, but Z99.2 (dependence on renal dialysis) is absent from the claim. The claim is flagged as incomplete.
Fix: Z99.2 must accompany N18.6 on every claim for an active dialysis patient. Build Z99.2 into the practice’s ESRD billing template as a default paired code. It should never appear on a claim checklist as optional.
Denial 3: Combination Code Not Used for Diabetic or Hypertensive ESRD
A biller submits N18.6 alongside I10 (essential hypertension) as separate codes. ICD-10-CM convention requires the combination code I12.0 instead. Payer scrubbers reject the claim.
Fix: When the chart documents hypertension with ESRD, the code is I12.0 (not I10 + N18.6 separately). When diabetes causes ESRD, the code is E11.22 + N18.6. Educate coders on ICD-10’s assumed relationship convention between hypertension and CKD.
Denial 4: MCP Code Does Not Match Visit Count
CPT 90960 is billed for a month in which only two physician visits are documented. The code requires four or more face-to-face visits. The claim denies a claim edit mismatch.
Fix: Track monthly physician visit counts before selecting the MCP code. Reconcile visit logs against the code selected prior to claim submission each month. A one-code error costs the difference between 90960 and 90962 reimbursement and triggers post-payment audit risk.
Denial 5: Dialysis Session Codes and MCP Codes Billed in the Same Month
The practice bills 90960 (monthly capitation) and 90935 (dialysis session) for the same patient in the same month. Medicare denies one as a duplicate under the bundling rules.
Fix: Choose one billing model, either MCP or session-based, and apply it consistently for each patient across the full month. Document the billing model in the patient record and do not switch mid-month.
Denial 6: Comorbidity Codes Missing from Inpatient Claims
An ESRD patient is admitted with hyperkalemia and anemia. The coder submits N18.6 as the principal diagnosis without coding E87.5 (hyperkalemia) or D63.1 (anemia in CKD). The DRG lands in 686 (no CC/MCC) instead of 685.
Fix: After selecting the principal diagnosis, systematically review the H&P, consultant notes, and discharge summary for all documented comorbidities that affect management. Code each one that meets the UHDDS criteria as an additional diagnosis. This is not upcoding, but an accurate representation of the clinical encounter.
