What is ICD-10 code J99?

J99 is the ICD-10-CM diagnosis code for Respiratory disorders in diseases classified elsewhere. Respiratory problems that occur as a result of another disease or condition affecting the lungs and airways. It belongs to the ICD-10-CM chapter for diseases of the respiratory system (j00-j99). J99 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. J99 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. J99 is a payment HCC under the CMS risk adjustment model. Under the CMS-HCC V28 risk adjustment model it maps to Chronic Obstructive Pulmonary Disease with a community, non-dual, aged base RAF weight of 0.334. Under the older CMS-HCC V24 model it maps to Fibrosis of Lung and Other Chronic Lung Disorders at RAF 0.268. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. HCC Buddy maintains the V28 and V24 mapping, RAF weight, and MEAT documentation criteria for J99 sourced directly from the CMS-HCC model files.

Yes. J99 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. J99 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.

What is the V28 vs V24 difference for J99?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For J99, V28 maps to Chronic Obstructive Pulmonary Disease at RAF 0.334 while V24 mapped to Fibrosis of Lung and Other Chronic Lung Disorders at RAF 0.268. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting J99?

Always code the underlying disease first, then use J99 as a secondary code to indicate respiratory involvement This is a manifestation code and should never be used as a primary diagnosis code Because J99 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

J99 ICD-10 Code: Respiratory disorders in diseases

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupJ99Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the respiratory system (J00-J99) / Other diseases of the respiratory system (J96-J99)

J99

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

Respiratory disorders in diseases classified elsewhere

Respiratory problems that occur as a result of another disease or condition affecting the lungs and airways.

Buddy Insight

CMS-HCC V28

Mapped

HCC 280

Chronic Obstructive Pulmonary...

RAF 0.334

CMS-HCC V24

Mapped

HCC 112

Fibrosis of Lung and Other Ch...

RAF 0.268

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 112

Fibrosis of Lung and Other Ch...

RAF 0.0

RXHCC

Mapped

HCC 227

Sarcoidosis, Pulmonary Alveol...

RAF 0.0

Code Trumping

Basket needed

Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

J9Other diseases of the respiratory system (J96-J99)

J99Respiratory disorders in diseases classified elsewhere

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for J99 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for J99 in this effective period.

Related Child Codes

Official

ICD-10-CM does not list child codes under J99 for this display context.

Includes

Official

ICD-10-CM does not list Includes notes for J99 in this effective period.

Excludes 1

Official

respiratory disorders in:
amebiasis (A06.5)
blastomycosis (B40.0-B40.2)
candidiasis (B37.1)
coccidioidomycosis (B38.0-B38.2)

Code First

Official

underlying disease, such as:
amyloidosis (E85.-)
ankylosing spondylitis (M45.-)
congenital syphilis (A50.-)
cryoglobulinemia (D89.1)

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J99 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for J99 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation of respiratory disorder as a manifestation of another classified disease

The underlying disease must be documented and coded first (etiology-manifestation convention)

Specific respiratory manifestation described (interstitial lung disease, pleuritis, pulmonary vasculitis, etc.)

Clinical evidence supporting the causal relationship between the underlying disease and the respiratory condition

MEAT Support

HCC Buddy guidance

Provider documentation of respiratory disorder as a manifestation of another classified disease

The underlying disease must be documented and coded first (etiology-manifestation convention)

Specific respiratory manifestation described (interstitial lung disease, pleuritis, pulmonary vasculitis, etc.)

Clinical evidence supporting the causal relationship between the underlying disease and the respiratory condition

Audit Caution

HCC Buddy guidance

Using J99 as a primary diagnosis — it is a manifestation code that must always be sequenced secondary to the underlying disease

Failing to identify and code the underlying systemic disease first per etiology-manifestation coding conventions

Using J99 when a more specific respiratory code exists for the particular type of lung involvement

Not querying the provider to establish the causal link between the systemic disease and the respiratory disorder

Common Mistakes

HCC Buddy guidance

J84.9 — Interstitial pulmonary disease, unspecified: use when interstitial lung disease is primary, not secondary to another condition

J98.4 — Other disorders of lung: for non-specific lung conditions not due to classified diseases

J84.10 — Pulmonary fibrosis, unspecified: use for primary pulmonary fibrosis, not secondary to systemic disease

M32.13 — Lung involvement in systemic lupus erythematosus: a specific etiology code that would be sequenced before J99

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is J99 an HCC code?

Yes. J99 maps to Chronic Obstructive Pulmonary Disease under the CMS-HCC V28 risk adjustment model (and Fibrosis of Lung and Other Chronic Lung Disorders under V24).

HCC Category Mapping

V28HCC 280, Chronic Obstructive Pulmonary Disease

0.334

V24HCC 112, Fibrosis of Lung and Other Chronic Lung Disorders

0.268

ESRDHCC 112, Fibrosis of Lung and Other Chronic Lung Disorders

0.000

RxHCCHCC 227, Sarcoidosis, Pulmonary Alveolar Disorders

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for J99

For J99to 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 J99 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

J99 is the ICD-10-CM diagnosis code for respiratory disorders in diseases classified elsewhere. Respiratory problems that occur as a result of another disease or condition affecting the lungs and airways. J99 sits in the ICD-10-CM chapter for diseases of the respiratory system (j00-j99), within the section covering other diseases of the respiratory system (j96-j99).

Under the CMS-HCC V28 risk adjustment model, J99 maps to Chronic Obstructive Pulmonary Disease (HCC 280) with a community, non-dual, aged base RAF weight of 0.334. Under the older CMS-HCC V24 model, J99 maps to Fibrosis of Lung and Other Chronic Lung Disorders (HCC 112) with a community, non-dual, aged base RAF weight of 0.268. 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.

Always code the underlying disease first, then use J99 as a secondary code to indicate respiratory involvement. Because J99 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for J99 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Always code the underlying disease first, then use J99 as a secondary code to indicate respiratory involvement
•This is a manifestation code and should never be used as a primary diagnosis code

Clinical Significance

J99 is a manifestation code indicating respiratory disorders secondary to diseases classified elsewhere, such as systemic lupus erythematosus, rheumatoid arthritis, or amyloidosis affecting the lungs. This code captures the pulmonary impact of systemic diseases and is essential for accurately reflecting disease burden. It must always be sequenced after the underlying etiology code.

Documentation Requirements

✓Provider documentation of respiratory disorder as a manifestation of another classified disease
✓The underlying disease must be documented and coded first (etiology-manifestation convention)
✓Specific respiratory manifestation described (interstitial lung disease, pleuritis, pulmonary vasculitis, etc.)
✓Clinical evidence supporting the causal relationship between the underlying disease and the respiratory condition
✓Current treatment for both the underlying disease and the respiratory manifestation

Excludes 1, Do NOT code together

respiratory disorders in:
amebiasis (A06.5)
blastomycosis (B40.0-B40.2)
candidiasis (B37.1)
coccidioidomycosis (B38.0-B38.2)
cystic fibrosis with pulmonary manifestations (E84.0)
dermatomyositis (M33.01, M33.11)
histoplasmosis (B39.0-B39.2)
late syphilis (A52.72, A52.73)
polymyositis (M33.21)
Sjögren syndrome (M35.02)
systemic lupus erythematosus (M32.13)
systemic sclerosis (M34.81)
Wegener's granulomatosis (M31.30-M31.31)

Code First

underlying disease, such as:
amyloidosis (E85.-)
ankylosing spondylitis (M45.-)
congenital syphilis (A50.-)
cryoglobulinemia (D89.1)
early congenital syphilis (A50.0-)
plasminogen deficiency (E88.02)
schistosomiasis (B65.0-B65.9)

Commonly Confused Codes

•J84.9: Interstitial pulmonary disease, unspecified: use when interstitial lung disease is primary, not secondary to another condition
•J98.4: Other disorders of lung: for non-specific lung conditions not due to classified diseases
•J84.10: Pulmonary fibrosis, unspecified: use for primary pulmonary fibrosis, not secondary to systemic disease
•M32.13: Lung involvement in systemic lupus erythematosus: a specific etiology code that would be sequenced before J99

Code Hierarchy

└J99Respiratory disorders in diseases classified elsewhere

J99 ICD-10-CM Code: Respiratory disorders in diseases classified elsewhere

HCC Buddy Code Card

J99

Is J99 an HCC code?

HCC Category Mapping

MEAT Criteria for J99

What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Excludes 1, Do NOT code together

Code First

Commonly Confused Codes

Code Hierarchy

Open J99 in the Interactive Encoder