All PlansBilling CodesHigh impact
ICD-10 Diagnosis Codes Not Covered for Date of Services 10/1/2016 and Forward
Connecticut Medicaid (HUSKY Health)·Coding
Effective date
Oct 1, 2016
We identified it
Jun 20, 2026
Summary
Effective October 1, 2016, certain ICD-10 diagnosis codes are no longer valid for billing. Claims submitted with invalid diagnosis codes will be denied with EOB code 4027. Providers must use the AMA ICD-10-CM 2017 book to verify valid diagnosis codes for dates of service from October 1, 2016 forward.
Action Required
Immediately: Billing team must verify all ICD-10 diagnosis codes using the American Medical Association ICD-10-CM 2017 book before submitting claims for dates of service October 1, 2016 and forward. Update billing system validation rules to prevent submission of invalid diagnosis codes. Claims with invalid codes will be denied with EOB code 4027.