J45.20: Mild intermittent asthma, uncomplicated

The ICD-10-CM code for mild intermittent asthma when the encounter documents no acute exacerbation and no status asthmaticus.

Billable

FY2027

TABLE OF CONTENTS

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At a glance

Code Family

J45: Asthma

Condition

Asthma

Billable

Yes, valid for HIPAA-covered transactions with no further characters required.

HCC Mapping (v28)

None, carrying no risk adjustment weight under CMS-HCC v28 or CMS-HCC v24.

DRG Grouping

MS-DRG 202 or 203 under the FY2027 MS-DRG v44 grouper, depending on complications and comorbidities.

Family Specificity

Eighteen billable codes across five severity tiers, with each tier split by the acuity documented at the encounter.

Which J45 code do I assign?

The J45 family splits first on the severity tier the provider documents, then on the acuity present at the encounter. Severity comes from provider documentation rather than from coder application of clinical criteria.

When documentation says…

Code

Mild intermittent asthma, stable, no exacerbation

J45.20

Mild intermittent asthma, uncomplicated. The note must state the mild intermittent severity tier and must record no acute exacerbation and no status asthmaticus.

Acute exacerbation of mild intermittent asthma

J45.21

Mild intermittent asthma with acute exacerbation. Assign this code wherever the note documents an exacerbation at the encounter.

Status asthmaticus in a patient with mild intermittent asthma

J45.22

Mild intermittent asthma with status asthmaticus. Status asthmaticus is the highest acuity within the tier and must be documented by the provider.

Mild persistent asthma

J45.30

Mild persistent asthma, uncomplicated. Each persistent tier carries its own uncomplicated, exacerbation and status asthmaticus child codes.

Moderate persistent asthma

J45.40

Moderate persistent asthma, uncomplicated. Assigning J45.20 where the provider documents moderate persistent asthma understates the documented severity.

Severe persistent asthma

J45.50

Severe persistent asthma, uncomplicated. The severe persistent codes are the only asthma codes that map to an HCC under CMS-HCC v28.

Wheezing with no confirmed asthma diagnosis

R06.2

Wheezing. The Excludes1 note at category J45 directs wheezing NOS to R06.2 rather than to an asthma code.

Tabular notes

EXCLUDES1

Category J45 carries Excludes1 notes that J45.20 inherits. An Excludes1 note means the excluded condition is not reported at the same time as an asthma code for the same condition. The excluded conditions are detergent asthma, J69.8, miner's asthma, J60, wood asthma, J67.8, and wheezing NOS, R06.2. Wheezing without a confirmed asthma diagnosis is coded to R06.2 rather than to J45.20.

EXCLUDES2

Category J45 carries an Excludes2 note for other specified chronic obstructive pulmonary disease, J44.89. An Excludes2 note means the excluded condition is not part of asthma but may co-exist with it. The note covers asthma with chronic obstructive pulmonary disease, chronic asthmatic obstructive bronchitis and chronic obstructive asthma. Where the record documents both asthma and COPD overlap, assign J45.20 and J44.89 together.

FY2027: EFFECTIVE 1 OCTOBER 2026

The Excludes2 note under category J45 names J44.89, other specified chronic obstructive pulmonary disease. Asthma and COPD may be reported together where both conditions are independently documented. No child codes were added to or deleted from category J45 in FY2026. The FY2027 codes and tabular addenda make no addition, deletion or revision in category J45.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

J45.20 does not map to any HCC category under CMS-HCC v28.

J45.20 did not map to any HCC category under CMS-HCC v24 either. The v24 to v28 transition changed nothing for this code.

Mild intermittent asthma contributes no risk adjustment weight to a Medicare Advantage risk score.

The severe persistent asthma codes, J45.50, J45.51 and J45.52, are the asthma codes that carry an HCC under CMS-HCC v28.

Asthma severity should be documented explicitly at each encounter so that coding reflects the highest clinically supported severity level.

MS-DRG v44 (FY2027)

MS-DRG 202: Bronchitis and asthma with CC/MCC.

MS-DRG 203: Bronchitis and asthma without CC/MCC.

Inpatient admissions with J45.20 as the principal diagnosis group to MS-DRG 202 or 203 in MDC 4 under the FY2027 MS-DRG v44 grouper. The source is Appendix B of the CMS MS-DRG Definitions Manual Version 44.0.

Assignment depends on the full diagnostic and procedural code set for the encounter.

J45.21, acute exacerbation, and J45.22, status asthmaticus, are each a CC under MS-DRG v44 (FY2027), per CMS Table 6J. Neither is on the Table 6I MCC list.

Medicare and commercial payers

J45.20 is a valid diagnosis code for Medicare Part A and Part B claims.

Coverage for asthma management services such as spirometry and allergy testing is governed by National Coverage Determinations and Local Coverage Determinations.

Biologic therapies for severe asthma are covered under Medicare Part B when administered and under Part D in self-administered form.

Biologic eligibility criteria reference documentation of severe persistent asthma, the J45.5- codes, rather than mild intermittent asthma.

WHERE SPECIFICITY IS LOST

J45.909, unspecified asthma, uncomplicated, records asthma without a severity tier or a complication. Where the provider documents mild intermittent severity, J45.20 is the specific code.

Assigning J45.20 where the note documents an acute exacerbation understates the acuity and bypasses J45.21.

Assigning J45.20 where the provider documents moderate or severe persistent asthma understates the severity. Severe persistent asthma is the only asthma severity tier that carries risk adjustment weight. That documentation gap removes HCC capture for the encounter.

Recording a severity tier above what the clinical documentation supports is inappropriate. Severity is set by provider documentation, not by coder interpretation.

Documentation checklist to support J45.20

Chart elements that support code selection and reduce specificity-driven denials.

A diagnosis of asthma stated by the provider.

The severity tier documented explicitly as mild intermittent.

Documentation that no acute exacerbation is present at the encounter, such as uncomplicated or stable language.

Documentation that no status asthmaticus is present at the encounter.

Severity recorded by the provider rather than inferred by the coder from NAEPP or GINA frequency thresholds.

An interval change in severity reflected in updated documentation, where the tier has moved since the last encounter.

Where COPD overlap is documented, the COPD diagnosis recorded independently to support reporting J44.89 alongside J45.20.

Where wheezing is the only finding, confirmation that an asthma diagnosis has been established, since wheezing alone directs the encounter to R06.2.

FAQ

Is J45.20 a billable code?

Yes. J45.20 is a valid billable code for HIPAA-covered transactions. No further characters are required.

When do I use J45.21 instead of J45.20?

Use J45.21 where the note documents an acute exacerbation of mild intermittent asthma. Use J45.20 where the encounter is stable and no exacerbation is documented. Where status asthmaticus is documented, J45.22 applies instead.

Does J45.20 map to an HCC?

No. J45.20 carries no HCC category under CMS-HCC v28, and it carried none under CMS-HCC v24. It contributes no risk adjustment weight. The severe persistent asthma codes, J45.50, J45.51 and J45.52, are the asthma codes that map to an HCC under CMS-HCC v28.

Can J45.20 and J44.89 be coded together?

Yes. The Excludes2 note at category J45 permits it. An Excludes2 note means the excluded condition is not part of asthma but may co-exist with it. Where the record documents both asthma and COPD overlap, assign both codes.

Does the provider need to document severity at every encounter?

Document it at each encounter where possible. Guideline I.A.19 bases code assignment on the provider's diagnostic statement. Where the record states no severity tier, uncomplicated asthma is coded to J45.909, which carries Asthma NOS as its inclusion term. The Index sends asthma with exacerbation to J45.901 and asthma with status asthmaticus to J45.902. An interval change in severity should be reflected in updated documentation.

How do I sequence J45.20 with J44.89?

Sequence on the primary clinical reason for the encounter. Both codes may be reported. The order follows the chief complaint and the applicable UHDDS or outpatient coding guidelines.

How does J45.20 differ between outpatient and inpatient coding?

In the outpatient setting J45.20 supports routine asthma follow-up where the disease is stable. For an exacerbation visit, assign J45.21. On the inpatient side, document severity at admission and at discharge. Acute exacerbation may qualify as a CC and status asthmaticus may qualify as an MCC in applicable DRG groupings. Verify both against the CMS MS-DRG Version 43 CC and MCC list.

What changed for J45.20 in FY2027?

J45.20 is unchanged in the FY2027 update. No child codes were added to or deleted from category J45 in FY2026. The Excludes2 note under category J45 names J44.89, other specified chronic obstructive pulmonary disease. The FY2027 codes and tabular addenda, effective 1 October 2026, make no addition, deletion or revision in category J45.

Related codes

Codes in the same family as J45.20. Only codes with a published page render as links.

Sibling codes in the J45 family

J45.21: Mild intermittent asthma with (acute) exacerbation.
J45.22: Mild intermittent asthma with status asthmaticus.
J45.30: Mild persistent asthma, uncomplicated.
J45.31: Mild persistent asthma with (acute) exacerbation.
J45.32: Mild persistent asthma with status asthmaticus.
J45.40: Moderate persistent asthma, uncomplicated.
J45.41: Moderate persistent asthma with (acute) exacerbation.
J45.42: Moderate persistent asthma with status asthmaticus.
J45.50: Severe persistent asthma, uncomplicated.
J45.51: Severe persistent asthma with (acute) exacerbation.
J45.52: Severe persistent asthma with status asthmaticus.
J45.901: Unspecified asthma with (acute) exacerbation.
J45.902: Unspecified asthma with status asthmaticus.
J45.909: Unspecified asthma, uncomplicated.
J45.990: Exercise induced bronchospasm.
J45.991: Cough variant asthma.
J45.998: Other asthma.

Additional codes to consider

Codes outside the J45 family considered alongside J45.20.

Companion: code alongside when documented

J44.89: Other specified chronic obstructive pulmonary disease, where asthma and COPD overlap is documented.

Consider instead

J45.21: Mild intermittent asthma with (acute) exacerbation, where an exacerbation is documented at the encounter.
J45.22: Mild intermittent asthma with status asthmaticus, where status asthmaticus is documented.
J45.30: Mild persistent asthma, uncomplicated, where the documented tier is mild persistent.
J45.40: Moderate persistent asthma, uncomplicated, where the documented tier is moderate persistent.
J45.50: Severe persistent asthma, uncomplicated, where the documented tier is severe persistent.
J45.909: Unspecified asthma, uncomplicated, where the note states no severity tier.
R06.2: Wheezing, where no asthma diagnosis has been established.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software