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T40.2X4A ICD-10-CM Code: Poisoning by other opioids, undetermined, initial encounter

T40.2X4A maps to CMS-HCC V28 137. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

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FY 2026 Apr update / Injury, poisoning and certain other consequences of external causes (S00-T88) / Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50)

T40.2X4A

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

Poisoning by other opioids, undetermined, initial encounter

Poisoning by other opioids, undetermined, initial encounter

CMS-HCC V28

HCC 137

Code-level coefficient reference

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
T40.2XPoisoning by, adverse effect of and underdosing of other opioids
T40.2X4Poisoning by other opioids, undetermined
T40.2X4APoisoning by other opioids, undetermined, initial encounter

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for T40.2X4A in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for T40.2X4A in this effective period.

Related Child Codes

Official
T40.2X4DPoisoning by other opioids, undetermined, subsequent encounter
T40.2X4SPoisoning by other opioids, undetermined, sequela

Includes

Official

ICD-10-CM does not list Includes notes for T40.2X4A in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for T40.2X4A in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for T40.2X4A in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for T40.2X4A in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for T40.2X4A in this effective period.

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 T40.2X4A an HCC code?

Yes. T40.2X4A (Poisoning by other opioids, undetermined, initial encounter) 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: T40.2X4A 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
T40.2X4A
Description
Poisoning by other opioids, undetermined, initial encounter
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 T40.2X4A in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for T40.2X4A

For T40.2X4A to 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 T40.2X4A during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

T40.2X4A is the ICD-10-CM diagnosis code for poisoning by other opioids, undetermined, initial encounter. T40.2X4A sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (t36-t50).

Under the CMS-HCC V28 risk adjustment model, T40.2X4A 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. No V24 mapping is shown for T40.2X4A; use the applicable model and payment year when reviewing the V28 mapping. 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. 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.

Coders should report T40.2X4A only when the provider documentation supports the specific condition described, since more specific codes within the same hierarchy can capture additional clinical detail. Because T40.2X4A maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 T40.2X4A sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Child Codes

T40.2X4APoisoning by other opioids, undetermined, initial encounter
HCC 137
T40.2X4DPoisoning by other opioids, undetermined, subsequent encounter
T40.2X4SPoisoning by other opioids, undetermined, sequela

Code Hierarchy

└T40Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]└T40.2Poisoning by, adverse effect of and underdosing of other opioids└T40.2XPoisoning by, adverse effect of and underdosing of other opioids└T40.2X4Poisoning by other opioids, undetermined└T40.2X4APoisoning by other opioids, undetermined, initial encounter
└T40.2X4APoisoning by other opioids, undetermined, initial encounter

Because T40.2X4A maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment.

T40.2X4A 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 T40.2X4A. 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.

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