F16.21 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 · HCC Buddy coding tools

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 lookupF16.21

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

F16.21

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

Hallucinogen dependence, in remission

A person who was dependent on hallucinogenic drugs is now in remission, meaning they are no longer actively using or dependent on these substances.

Buddy Insight

Hallucinogen dependence in remission indicates a patient who has achieved sustained recovery from hallucinogen dependence.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 137

Drug Use Disorder, Moderate/S...

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

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 082

HHS-HCC 082 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 55

Substance Use Disorder/Modera...

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

F16Hallucinogen related disorders F16.2Hallucinogen dependence F16.21Hallucinogen dependence, in remission

Inclusion Terms

Official

Other hallucinogen use disorder, moderate, in early remission
Other hallucinogen use disorder, moderate, in sustained remission
Other hallucinogen use disorder, severe, in early remission
Other hallucinogen use disorder, severe, in sustained remission
Phencyclidine use disorder, moderate, in early remission
Phencyclidine use disorder, moderate, in sustained remission
Phencyclidine use disorder, severe, in early remission
Phencyclidine 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

F16.20Hallucinogen dependence, uncomplicated F16.22Hallucinogen dependence with intoxication F16.24Hallucinogen dependence with hallucinogen-induced mood disorder F16.25Hallucinogen dependence with hallucinogen-induced psychotic disorder F16.28Hallucinogen dependence with other hallucinogen-induced disorder

Includes

Official

disorders of psychological developmentInherited from F01-F99, F16
ecstasyInherited from F01-F99, F16
PCPInherited from F01-F99, F16
phencyclidineInherited from F01-F99, F16

Excludes 1

Official

hallucinogen abuse (F16.1-)Inherited from F16.2
hallucinogen use, unspecified (F16.9-)Inherited from F16.2

Code First

Official

No Code First sequencing instructions are included in this display for F16.21. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F16.21. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F16.21. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Provider documentation of prior hallucinogen dependence

Explicit statement that the patient is 'in remission' — early or sustained

Duration of remission documented when available

Ongoing treatment or monitoring plan (counseling, support groups, follow-up visits)

MEAT Support

HCC Buddy guidance

Provider documentation of prior hallucinogen dependence

Explicit statement that the patient is 'in remission' — early or sustained

Duration of remission documented when available

Ongoing treatment or monitoring plan (counseling, support groups, follow-up visits)

Audit Caution

HCC Buddy guidance

Coding active dependence (F16.20) when the patient is actually in remission

Using a history code (Z86.59) instead of the remission code, losing HCC capture

Not confirming whether remission from dependence (F16.21) vs abuse (F16.11) is documented

Assuming remission means the condition is resolved — it still requires ongoing coding and monitoring

Common Mistakes

HCC Buddy guidance

F16.20 — Hallucinogen dependence, uncomplicated; use for active dependence without current complications

F16.11 — Hallucinogen abuse, in remission; use when the prior condition was abuse not dependence

Z86.59 — Personal history of other mental and behavioral disorders; this is less specific and not preferred when remission status is documented

F16.90 — Hallucinogen use, unspecified; does not capture dependence or remission status

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 F16.21 an HCC code?

Yes. F16.21 (Hallucinogen 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: F16.21 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: F16.21
Description: Hallucinogen 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 F16.21 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for F16.21

For F16.21, 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

F16.21 is the ICD-10-CM diagnosis code for hallucinogen dependence, in remission. A person who was dependent on hallucinogenic drugs is now in remission, meaning they are no longer actively using or dependent on these substances. F16.21 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, F16.21 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.

Use this code when the patient has achieved sustained abstinence or controlled use after hallucinogen dependence. For F16.21, 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 F16.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code when the patient has achieved sustained abstinence or controlled use after hallucinogen dependence
•Document the length and type of remission (early or sustained) if available in the clinical record

Clinical Significance

Hallucinogen dependence in remission indicates a patient who has achieved sustained recovery from hallucinogen dependence. This remains clinically significant because it reflects ongoing relapse risk and need for continued monitoring, support services, and substance abuse follow-up.

Documentation Requirements

✓Provider documentation of prior hallucinogen dependence
✓Explicit statement that the patient is 'in remission' — early or sustained
✓Duration of remission documented when available
✓Ongoing treatment or monitoring plan (counseling, support groups, follow-up visits)
✓Assessment of relapse risk factors

Commonly Confused Codes

•F16.20: Hallucinogen dependence, uncomplicated; use for active dependence without current complications
•F16.11: Hallucinogen abuse, in remission; use when the prior condition was abuse not dependence
•Z86.59: Personal history of other mental and behavioral disorders; this is less specific and not preferred when remission status is documented
•F16.90: Hallucinogen use, unspecified; does not capture dependence or remission status