Z89.421 ICD-10-CM Code: Acquired absence of other right toe(s)
HCC Buddy Code Card
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FY 2026 Apr update / Factors influencing health status and contact with health services (Z00-Z99) / Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99)
Z89.421
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceAcquired absence of other right toe(s)
A person who has lost one or more of the smaller toes (not the big toe) on their right foot due to amputation or other acquired cause.
Buddy Insight
Acquired absence of other right toes (excluding great toe) impacts balance and gait mechanics, though typically less severely than great toe amputation.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
MappedHCC 189
RAF 0.350
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 189
RAF 0.0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for Z89.421 in this effective period.
Excludes 2
Official- acquired absence of great toe (Z89.41-)
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for Z89.421 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for Z89.421 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for Z89.421 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for Z89.421 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for Z89.421 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is Z89.421 an HCC code?
Yes. Z89.421 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 Z89.421
For Z89.421to 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 Z89.421 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
Z89.421 is the ICD-10-CM diagnosis code for acquired absence of other right toe(s). A person who has lost one or more of the smaller toes (not the big toe) on their right foot due to amputation or other acquired cause. Z89.421 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, Z89.421 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.
This code is for toes other than the great toe; use Z89.411-Z89.419 for great toe loss. Because Z89.421 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 Z89.421 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Acquired absence of other right toes (excluding great toe) impacts balance and gait mechanics, though typically less severely than great toe amputation. This condition often indicates progression of underlying vascular or diabetic complications requiring ongoing monitoring for further deterioration.
Documentation Requirements
- ✓Acquired nature of toe absence documented
- ✓Right side laterality specified
- ✓Specific toes involved identified when possible
- ✓Great toe specifically excluded from absence
- ✓Underlying cause or etiology documented
- ✓Functional assessment of current mobility
- ✓Prosthetic or orthotic device use noted
- ✓Associated wound care or complications