2026 ICD-10-CM Diagnosis Code C23Malignant neoplasm of gallbladder

ICD-10-CM Codes›C00–D49›C15-C26›C23

ICD-10-CM C23
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C23 is a billable ICD-10-CM diagnosis code for malignant neoplasm of gallbladder. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 435 through 437. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 21 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - gallbladder.

For Medicare Advantage risk adjustment, C23 maps to CMS-HCC Category 20 (Lung and Other Severe Cancers) under the V28 model, adding a risk factor of about 1.136 for a community, non-dual, aged beneficiary in payment year 2026.

Code Identity

ICD-10-CM Code
C23
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of gallbladder
Short Description
Malignant neoplasm of gallbladder
Same as the full description in the CMS dataset.
Chapter
C15-C26
Malignant neoplasms of digestive organs

Code Classification

ChapterC00–D49Neoplasms
SectionC15-C26Malignant neoplasms of digestive organs
CategoryC23Malignant neoplasm of gallbladder
This CodeC23Malignant neoplasm of gallbladder

Medicare Risk Adjustment (HCC)Billing

C23 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.

CMS-HCC V28 Category (Payment Model)
HCC 20— Lung and Other Severe Cancers
Payment HCC · PY 2026 one of 233 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+1.136
community, non-dual, aged · ranges 0.672–1.214 across segments
Hierarchy
Superseded by HCC 17, HCC 18, and HCC 19
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 9
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 9 · ESRD (V21): HCC 9 · ESRD (V24): HCC 9
ESRD V21 weights: 0.169 dialysis, 0.604–0.975 functioning graft · ESRD V24 weights: 0.181 dialysis, 0.770–1.226 functioning graft
Part D (RxHCC)
RxHCC 22 — Prostate, Breast, Bladder, and Other Cancers and Tumors
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carcinoma of gallbladder
  • Local recurrence of malignant neoplasm of gallbladder
  • Malignant mesenchymal neoplasm of gallbladder
  • Malignant neoplasm of gallbladder
  • Primary adenocarcinoma of gallbladder
  • Primary carcinoma liver and/or biliary system
  • Primary carcinoma of gallbladder
  • Primary malignant mesenchymal neoplasm of gallbladder
  • Primary malignant neoplasm of gallbladder
  • Primary squamous cell carcinoma of gallbladder and extrahepatic biliary tract
  • Squamous cell carcinoma of gallbladder and extrahepatic biliary tract

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO019
Gastrointestinal cancers - gallbladder
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Acalculous Cholecystitis

    inflammation of the gallbladder wall in the absence of gallstones.

  • Biliary Dyskinesia

    a motility disorder characterized by biliary colic, absence of gallstones, and an abnormal gallbladder ejection fraction. it is caused by gallbladder dyskinesia and/or sphincter of oddi dysfunction.

  • Cholecystitis

    inflammation of the gallbladder; generally caused by impairment of bile flow, gallstones in the biliary tract, infections, or other diseases.

  • Gallbladder

    a storage reservoir for bile secretion. gallbladder allows the delivery of bile acids at a high concentration and in a controlled manner, via the cystic duct to the duodenum, for degradation of dietary lipid.

  • Gallbladder Diseases

    diseases of the gallbladder. they generally involve the impairment of bile flow, gallstones in the biliary tract, infections, neoplasms, or other diseases.

  • Gallbladder Emptying

    a process whereby bile is delivered from the gallbladder into the duodenum. the emptying is caused by both contraction of the gallbladder and relaxation of the sphincter mechanism at the choledochal terminus.

  • Gallbladder Neoplasms

    tumors or cancer of the gallbladder.

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
gallbladderC23C78.89D01.5D13.5D37.6D49.0

Patient EducationClinical

Gallbladder Cancer

Your gallbladder is a pear-shaped organ under your liver. It stores bile, a fluid made by your liver to digest fat. As your stomach and intestines digest food, your gallbladder releases bile through a tube called the common bile duct. The duct connects your gallbladder and liver to your small intestine.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C23 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
156.0 Malig neo gallbladder
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C23Overview

What is the ICD-10 code for malignant neoplasm of gallbladder?

The ICD-10-CM code for malignant neoplasm of gallbladder is C23. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is C23 (Malignant neoplasm of gallbladder) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of gallbladder on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C23 group to?

When malignant neoplasm of gallbladder is the principal diagnosis on an inpatient stay, it groups to MS-DRG 435, 436, 437, with relative weights from 0.8533 to 1.8367 depending on complications. Higher weights mean higher Medicare reimbursement.

Is C23 a CC or MCC?

CMS lists C23 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 21 closely related codes in its exclusion list.

What is the ICD-9 equivalent of C23?

Under the General Equivalence Mappings, malignant neoplasm of gallbladder converts to ICD-9-CM 156.0 (malig neo gallbladder). The mapping is a direct match.

What HCC is C23?

C23 (malignant neoplasm of gallbladder) maps to CMS-HCC Category 20 (Lung and Other Severe Cancers), commonly written as HCC 20, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 9 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.

Does C23 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, C23 adds a risk adjustment factor of about 1.136 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.672 to 1.214 depending on the payment segment). A more severe related category (HCC 17, HCC 18, and HCC 19) supersedes it when both are reported. See the full factor table on the HCC 20 category page.