What is ICD-10 code C24.0?

C24.0 is the ICD-10-CM diagnosis code for Malignant neoplasm of extrahepatic bile duct. Cancer that starts in the bile ducts outside the liver. These ducts carry bile from the liver and gallbladder to the small intestine. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C24.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C24.0 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C24.0 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C24.0 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C24.0 map to under V28?

C24.0 maps to CMS-HCC V28 HCC 20 (Lung and Other Severe Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C24.0: Malignant neoplasm

C24.0 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupC24.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of digestive organs (C15-C26)

C24.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of extrahepatic bile duct

Cancer that starts in the bile ducts outside the liver. These ducts carry bile from the liver and gallbladder to the small intestine.

Buddy Insight

Malignant neoplasm of the extrahepatic bile duct (extrahepatic cholangiocarcinoma) includes cancers of the common hepatic duct, common bile duct, and cystic duct outside the liver parenchyma.

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 009

HHS-HCC 009 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 9

Lung and Other Severe Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 22

Prostate, Breast, Bladder, an...

Code-level coefficient reference

Code Book Path

Official

C24Malignant neoplasm of other and unspecified parts of biliary tract

C24.0Malignant neoplasm of extrahepatic bile duct

Inclusion Terms

Official

Malignant neoplasm of biliary duct or passage NOS
Malignant neoplasm of common bile duct
Malignant neoplasm of cystic duct
Malignant neoplasm of hepatic duct

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C24.0 in this effective period.

Related Child Codes

Official

C24.1Malignant neoplasm of ampulla of Vater

C24.8Malignant neoplasm of overlapping sites of biliary tract

C24.9Malignant neoplasm of biliary tract, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for C24.0 in this effective period.

Excludes 1

Official

malignant neoplasm of intrahepatic bile duct (C22.1)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C24.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C24.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C24.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation confirming extrahepatic bile duct as the primary tumor location

Specific location within the extrahepatic ducts (perihilar vs distal)

Bismuth-Corlette classification for perihilar tumors if applicable

Histological confirmation of carcinoma

MEAT Support

HCC Buddy guidance

Documentation confirming extrahepatic bile duct as the primary tumor location

Specific location within the extrahepatic ducts (perihilar vs distal)

Bismuth-Corlette classification for perihilar tumors if applicable

Histological confirmation of carcinoma

Audit Caution

HCC Buddy guidance

Confusing intrahepatic (C22.1) with extrahepatic (C24.0) cholangiocarcinoma — the liver parenchymal boundary is the dividing line

Coding Klatskin tumor as intrahepatic when it is classified as extrahepatic (perihilar)

Not distinguishing bile duct obstruction from bile duct cancer — obstruction may be from external compression

Coding pancreatic head cancer causing bile duct obstruction as bile duct cancer

Common Mistakes

HCC Buddy guidance

C22.1 — Intrahepatic bile duct carcinoma: intrahepatic cholangiocarcinoma occurs within the liver; C24.0 is for ducts outside the liver

C24.1 — Ampulla of Vater: the ampulla is the distal opening; cancers of the ampulla have different prognosis and treatment

C23 — Gallbladder cancer: the gallbladder connects to the bile duct via the cystic duct; verify primary site

C25.0 — Head of pancreas: pancreatic head tumors may compress or invade the bile duct; code the primary site

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C24.0 an HCC code?

Yes. C24.0 (Malignant neoplasm of extrahepatic bile duct) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C24.0 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C24.0
Description: Malignant neoplasm of extrahepatic bile duct
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

ESRDHCC 9, Lung and Other Severe Cancers

Not separately weighted

RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C24.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for C24.0

For C24.0 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C24.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C24.0 is the ICD-10-CM diagnosis code for malignant neoplasm of extrahepatic bile duct. Cancer that starts in the bile ducts outside the liver. These ducts carry bile from the liver and gallbladder to the small intestine. C24.0 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).

Under the CMS-HCC V28 risk adjustment model, C24.0 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C24.0; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Distinguish from intrahepatic bile duct cancer (C22.1) which occurs within the liver. Because C24.0 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for C24.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Distinguish from intrahepatic bile duct cancer (C22.1) which occurs within the liver
•Document the specific location and stage of the tumor for accurate coding and treatment planning

Clinical Significance

Malignant neoplasm of the extrahepatic bile duct (extrahepatic cholangiocarcinoma) includes cancers of the common hepatic duct, common bile duct, and cystic duct outside the liver parenchyma. This includes the clinically important Klatskin tumor (perihilar cholangiocarcinoma), which occurs at the hepatic duct bifurcation. These cancers are significant for risk adjustment because they are aggressive, often unresectable at presentation, and require complex multidisciplinary management.

Documentation Requirements

✓Documentation confirming extrahepatic bile duct as the primary tumor location
✓Specific location within the extrahepatic ducts (perihilar vs distal)
✓Bismuth-Corlette classification for perihilar tumors if applicable
✓Histological confirmation of carcinoma
✓Stage of disease and resectability assessment

Commonly Confused Codes

•C22.1: Intrahepatic bile duct carcinoma: intrahepatic cholangiocarcinoma occurs within the liver; C24.0 is for ducts outside the liver
•C24.1: Ampulla of Vater: the ampulla is the distal opening; cancers of the ampulla have different prognosis and treatment
•C23: Gallbladder cancer: the gallbladder connects to the bile duct via the cystic duct; verify primary site
•C25.0: Head of pancreas: pancreatic head tumors may compress or invade the bile duct; code the primary site