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F18.21 ICD-10-CM Code: Inhalant dependence, in remission

F18.21 maps to CMS-HCC V28 137. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

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Code lookupF18.21

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Mental and behavioral disorders due to psychoactive substance use (F10-F19)

F18.21

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

Inhalant dependence, in remission

A person who was dependent on inhalants but has successfully stopped using them and maintained abstinence for a sustained period.

Buddy the Bee presenting code insight

Buddy Insight

Inhalant dependence in remission indicates a patient who has achieved recovery from inhalant dependence.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 137

Coefficient HCC 137: 0.424 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 082

Code-level coefficient reference

ESRD/PACE

HCC 55

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
F18Inhalant related disordersF18.2Inhalant dependenceF18.21Inhalant dependence, in remission

Inclusion Terms

Official
  • Inhalant use disorder, moderate, in early remission
  • Inhalant use disorder, moderate, in sustained remission
  • Inhalant use disorder, severe, in early remission
  • Inhalant use disorder, severe, in sustained remission

Excludes 2

Official
  • symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)Inherited from F01-F99

Related Codes

Official
F18.20Inhalant dependence, uncomplicatedF18.22Inhalant dependence with intoxicationF18.24Inhalant dependence with inhalant-induced mood disorderF18.25Inhalant dependence with inhalant-induced psychotic disorderF18.27Inhalant dependence with inhalant-induced dementia

Includes

Official
  • disorders of psychological developmentInherited from F01-F99, F18
  • volatile solventsInherited from F01-F99, F18

Excludes 1

Official
  • inhalant abuse (F18.1-)Inherited from F18.2
  • inhalant use, unspecified (F18.9-)Inherited from F18.2

Code First

Official

No Code First sequencing instructions are included in this display for F18.21. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F18.21. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F18.21. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of prior inhalant dependence
Provider statement of remission status (early vs sustained)
Duration of remission
Monitoring plan for residual neurological and organ damage

MEAT Support

HCC Buddy guidance
Documentation of prior inhalant dependence
Provider statement of remission status (early vs sustained)
Duration of remission
Monitoring plan for residual neurological and organ damage

Audit Caution

HCC Buddy guidance
Coding active dependence when remission has been achieved
Using a Z-code history instead of the remission code — loses HCC capture
Confusing remission from dependence with remission from abuse
Not continuing to code and monitor the condition annually despite remission

Common Mistakes

HCC Buddy guidance
F18.20 — Inhalant dependence, uncomplicated; use for active dependence
F18.11 — Inhalant abuse, in remission; use when the prior condition was abuse not dependence
Z86.59 — Personal history of mental and behavioral disorders; less specific, loses HCC capture
F18.90 — Inhalant use, unspecified; does not capture dependence or remission

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is F18.21 an HCC code?

Yes. F18.21 (Inhalant dependence, in remission) maps to HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.424. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: F18.21 is billable and maps to V28 HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
F18.21
Description
Inhalant dependence, in remission
HCC (V28)
HCC 137 — Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications
RAF reference coefficient
0.424
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications
0.424
ESRDHCC 55, Substance Use Disorder/Moderate/Severe/Substance Use with Complications
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work F18.21 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for F18.21

For F18.21, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • 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

Coder workflow notes

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What This Code Means

F18.21 is the ICD-10-CM diagnosis code for inhalant dependence, in remission. A person who was dependent on inhalants but has successfully stopped using them and maintained abstinence for a sustained period. F18.21 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering mental and behavioral disorders due to psychoactive substance use (f10-f19).

Under the CMS-HCC V28 risk adjustment model, F18.21 maps to Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications (HCC 137) with a source-labeled community, non-dual, aged reference coefficient of 0.424. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Document the length of remission when available (early vs sustained remission). For F18.21, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for F18.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Document the length of remission when available (early vs sustained remission)
  • •Remission codes indicate the patient is no longer actively using despite past dependence

Clinical Significance

Inhalant dependence in remission indicates a patient who has achieved recovery from inhalant dependence. Given the severe neurotoxic effects of chronic inhalant use, residual cognitive deficits, white matter changes, and organ damage may persist even in remission, requiring ongoing monitoring and rehabilitation.

Documentation Requirements

  • ✓Documentation of prior inhalant dependence
  • ✓Provider statement of remission status (early vs sustained)
  • ✓Duration of remission
  • ✓Monitoring plan for residual neurological and organ damage
  • ✓Relapse prevention plan
  • ✓Neurocognitive assessment results if available

Commonly Confused Codes

  • •F18.20: Inhalant dependence, uncomplicated; use for active dependence
  • •F18.11: Inhalant abuse, in remission; use when the prior condition was abuse not dependence
  • •Z86.59: Personal history of mental and behavioral disorders; less specific, loses HCC capture
  • •F18.90: Inhalant use, unspecified; does not capture dependence or remission

Child Codes

F18.20Inhalant dependence, uncomplicated
HCC 137
F18.21Inhalant dependence, in remission
HCC 137
F18.22Inhalant dependence with intoxication
F18.24Inhalant dependence with inhalant-induced mood disorder
HCC 137
F18.25Inhalant dependence with inhalant-induced psychotic disorder
F18.27Inhalant dependence with inhalant-induced dementia
HCC 135
F18.28Inhalant dependence with other inhalant-induced disorders
F18.29Inhalant dependence with unspecified inhalant-induced disorder
HCC 137

Code Hierarchy

└F18Inhalant related disorders└F18.2Inhalant dependence└F18.21Inhalant dependence, in remission
└F18.21Inhalant dependence, in remission

Also searched as

  • F18 21
  • F1821

For F18.21, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

F18.21 maps to CMS-HCC V28 category 137, Drug Use Disorder, Moderate/Severe, or Drug Use with Non-Psychotic Complications. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for F18.21. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

Work F18.21 in HCC Buddy

Open F18.21 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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