2026 ICD-10-CM Diagnosis Code J42Unspecified chronic bronchitis

ICD-10-CM Codes›J00–J99›J40-J4A›J42

ICD-10-CM J42
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

J42 is a billable ICD-10-CM diagnosis code for unspecified chronic bronchitis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 190 through 192. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chronic obstructive pulmonary disease and bronchiectasis.

For Medicare Advantage risk adjustment, J42 maps to CMS-HCC Category 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders) under the V28 model, adding a risk factor of about 0.319 for a community, non-dual, aged beneficiary in payment year 2026.

Code Identity

ICD-10-CM Code
J42
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified chronic bronchitis
Short Description
Unspecified chronic bronchitis
Same as the full description in the CMS dataset.
Chapter
J40-J4A
Chronic lower respiratory diseases

Code Classification

ChapterJ00–J99Diseases of the respiratory system
SectionJ40-J4AChronic lower respiratory diseases
CategoryJ42Unspecified chronic bronchitis
This CodeJ42Unspecified chronic bronchitis

Medicare Risk Adjustment (HCC)Billing

J42 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 280— Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders
Payment HCC · PY 2026 one of 79 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.319
community, non-dual, aged · ranges 0.209–0.390 across segments
Hierarchy
Superseded by HCC 276, HCC 277, HCC 278, and HCC 279
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 111
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 111 · ESRD (V21): HCC 111 · ESRD (V24): HCC 111
ESRD V21 weights: 0.072 dialysis, 0.299–0.313 functioning graft · ESRD V24 weights: 0.058 dialysis, 0.187–0.344 functioning graft
Part D (RxHCC)
RxHCC 229 — Chronic Obstructive Pulmonary Disease, Bronchiectasis, and Other Asthma
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.

  • Bronchiolitis obliterans syndrome due to and after lung transplantation
  • Bronchitis
  • Bronchitis co-occurrent with acute wheeze
  • Bronchitis co-occurrent with chronic wheeze
  • Bronchitis co-occurrent with wheeze
  • Chronic bronchiolitis
  • Chronic bronchitis
  • Chronic bronchitis co-occurrent with wheeze
  • Chronic graft-versus-host disease
  • Chronic obliterative bronchiolitis
  • Chronic tracheitis
  • Chronic tracheobronchitis
  • Eosinophilic bronchitis
  • Fetid chronic bronchitis
  • Infectious disorder of bronchus
  • Protracted bronchitis caused by bacterium
  • Septic bronchitis
  • Tracheobronchitis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Chronic bronchitis NOS
  • Chronic tracheitis
  • Chronic tracheobronchitis

Use Additional Code

  • code to identify:
  • exposure to environmental tobacco smoke Z77.22
  • exposure to tobacco smoke in the perinatal period P96.81
  • history of tobacco dependence Z87.891
  • occupational exposure to environmental tobacco smoke Z57.31
  • tobacco dependence F17
  • tobacco use Z72.0

Type 1 Excludes

  • bronchiolitis obliterans and bronchiolitis obliterans syndrome J44.81
  • chronic asthmatic bronchitis J44
  • chronic bronchitis with airways obstruction J44
  • chronic emphysematous bronchitis J44
  • chronic obstructive pulmonary disease NOS J44.9
  • simple and mucopurulent chronic bronchitis J41

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR RSP008
Chronic obstructive pulmonary disease and bronchiectasis
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Bronchitis

    inflammation of the large airways in the lung including any part of the bronchi, from the primary bronchi to the tertiary bronchi.

  • Bronchitis, Chronic

    a subcategory of chronic obstructive pulmonary disease. the disease is characterized by hypersecretion of mucus accompanied by a chronic (more than 3 months in 2 consecutive years) productive cough. infectious agents are a major cause of chronic bronchitis.

  • Infectious bronchitis virus

    a species of coronavirus causing infections in chickens and possibly pheasants. chicks up to four weeks old are the most severely affected.

  • Coronavirus

    a member of coronaviridae which causes respiratory or gastrointestinal disease in a variety of vertebrates.

  • Croup|Acute Obstructive Laryngitis|Laryngotracheitis|Laryngotracheobronchitis

    acute upper respiratory airways infection that results in the swelling of the larynx. it is usually caused by parainfluenza viruses. signs include a characteristic barking cough and stridor.

  • Tracheobronchitis

    inflammation of the tracheobronchial tree.

Patient EducationClinical

Chronic Bronchitis

Chronic bronchitis is a type of COPD (chronic obstructive pulmonary disease). COPD is a group of lung diseases that make it hard to breathe and get worse over time. The other main type of COPD is emphysema. Most people with COPD have both emphysema and chronic bronchitis, but how severe each type is can be different from person to person.

The full article covers:

  • What is chronic bronchitis?
  • What causes chronic bronchitis?
  • Who is at risk for chronic bronchitis?
  • What are the symptoms of chronic bronchitis?
  • How is chronic bronchitis diagnosed?
  • What are the treatments for chronic bronchitis?
  • Can chronic bronchitis be prevented?

Read the full article at MedlinePlus

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

Convert J42 to ICD-9-CMHistory

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

ICD-9-CM
491.9 Chronic bronchitis NOS
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 J42Overview

What is the ICD-10 code for unspecified chronic bronchitis?

The ICD-10-CM code for unspecified chronic bronchitis is J42. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is J42 (Unspecified chronic bronchitis) a billable code?

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

What MS-DRG does J42 group to?

When unspecified chronic bronchitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 190, 191, 192, with relative weights from 0.6420 to 1.1077 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of J42?

Under the General Equivalence Mappings, unspecified chronic bronchitis converts to ICD-9-CM 491.9 (chronic bronchitis NOS). The mapping is a direct match.

What HCC is J42?

J42 (unspecified chronic bronchitis) maps to CMS-HCC Category 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders), commonly written as HCC 280, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 111 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 229.

Does J42 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, J42 adds a risk adjustment factor of about 0.319 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.209 to 0.390 depending on the payment segment). A more severe related category (HCC 276, HCC 277, HCC 278, and HCC 279) supersedes it when both are reported. See the full factor table on the HCC 280 category page.