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ICD-10-CM 2027 diagnosis code

J42Unspecified chronic bronchitis

✓ Billable / specific

J42 is a valid, billable ICD-10-CM code for unspecified chronic bronchitis. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Chronic bronchitis, ICD-10 code for Pharyngotracheitis, ICD-10 code for Chronic tracheitis.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About J42

J42 is the ICD-10-CM diagnosis code for unspecified chronic bronchitis. It belongs to block J40-J4B (chronic lower respiratory diseases) and chapter 10 (diseases of the respiratory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Don't report J42 together with the conditions in its Excludes1 note: bronchiolitis obliterans and bronchiolitis obliterans syndrome (J44.81), chronic asthmatic bronchitis (J44.-), chronic bronchitis with airways obstruction (J44.-), chronic emphysematous bronchitis (J44.-) and 2 more.

Use an additional 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.-) and 1 more.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 190 (Chronic Obstructive Pulmonary Disease with MCC, relative weight 1.0748), DRG 191 (Chronic Obstructive Pulmonary Disease with CC, relative weight 0.8261) and DRG 192 (Chronic Obstructive Pulmonary Disease without CC/MCC, relative weight 0.6288), in MDC 04 (Diseases and Disorders of the Respiratory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 491.9 (unspecified chronic bronchitis).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Chronic bronchitis NOS
  • Chronic tracheitis
  • Chronic tracheobronchitis
Excludes1Not coded here — never report together with this code
  • 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.-)
Use additional codeAdd a secondary code to fully describe the condition
  • 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)
Code alsoTwo codes may be needed; sequencing depends on circumstances
  • , if applicable, chronic respiratory conditions due to chemicals, gases, fumes and vapors (J68.4)

Notes that apply from higher levels

Instructions written at a parent level also apply to J42.

Broader instructions also apply from J40-J4B Chronic lower respiratory diseases and Chapter 10: Diseases of the respiratory system.

Alphabetic index entries

11 entries

Terms in the official ICD-10-CM index that lead to J42.

Codes whose notes reference J42

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 491.9Unspecified chronic bronchitisexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about J42

Is J42 billable?

Yes. J42 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can J42 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict J42 as a principal diagnosis.

Is J42 a CC or MCC?

No. J42 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does J42 group to?

J42 is used in the MS-DRG v44.0 logic for MS-DRG 190 (Chronic Obstructive Pulmonary Disease with MCC), MS-DRG 191 (Chronic Obstructive Pulmonary Disease with CC) and MS-DRG 192 (Chronic Obstructive Pulmonary Disease without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for J42?

The CMS General Equivalence Mappings map J42 to ICD-9-CM 491.9.