Z89.412
BillableAcquired absence of left great toe
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Z89.412 an HCC code?
Yes. Z89.412 maps to Amputation Status, Lower Limb/Amputation Complications under the V24 model but is not retained in V28.
HCC Category Mapping
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 Z89.412
For Z89.412 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 Z89.412 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Z89.412 is the ICD-10-CM diagnosis code for acquired absence of left great toe. A person who has lost their left big toe due to amputation or other acquired cause. Z89.412 sits in the ICD-10-CM chapter for factors influencing health status and contact with health services (z00-z99), within the section covering persons with potential health hazards related to family and personal history and certain conditions influencing health status (z77-z99).
Under the older CMS-HCC V24 model, Z89.412 maps to Amputation Status, Lower Limb/Amputation Complications (HCC 189) with a community, non-dual, aged base RAF weight of 0.350. 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.
Verify laterality is clearly documented as left in the medical record. Because Z89.412 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 Z89.412 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify laterality is clearly documented as left in the medical record
- •Great toe loss can significantly impact balance and mobility; note this in clinical documentation
Clinical Significance
Acquired absence of left great toe represents a significant lower extremity amputation affecting balance, proprioception, and ambulation. This condition typically results from complications of diabetes, vascular disease, or trauma, indicating substantial underlying pathology requiring ongoing monitoring.
Documentation Requirements
- ✓Acquired nature of absence clearly documented
- ✓Specific laterality (left side) documented
- ✓Great toe specifically identified
- ✓Underlying cause or reason for amputation
- ✓Level of amputation if partial removal
- ✓Current functional status and mobility
- ✓Use of assistive devices or prosthetics
- ✓Impact on activities of daily living