CurrentMolina HealthcarePolicy N/A

ICD-10 First-Listed (Primary) Diagnosis Coding for Reimbursement

Governance of which ICD-10-CM diagnosis codes may be used as the principal/first-listed diagnosis on claims and coding sequencing rules that affect provider reimbursement for Molina Healthcare; applies to providers submitting claims to Molina.

Policy Summary

PayerMolina Healthcare

PolicyICD-10 First-Listed (Primary) Diagnosis Coding for Reimbursement

Policy CodePolicy N/A

Change TypeVerified links and template update (12/12/2024)

Effective DateNov 20, 2020

Next Review Date

Key ActionProviders must follow ICD-10-CM Official Guidelines and standard coding practices to avoid claim denials and potential payment recovery.

SourceLink

POLICY UPDATE CHANGES

Verified links and codes (08/20/2023).

Verified links and updated Template (12/12/2024).

New Policy effective 11/20/2020.

3document revision entries listed in Documentation History

1primary purpose statement (reimbursement focus)

1explicit coding guidance section title present

ICD-10 First-Listed (Primary) Diagnosis Criteria

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Providers must follow industry standard coding practices and the ICD-10-CM Official Guidelines; improper billing or coding may result in claim rejection/denial and Molina may recover payments.

The term 'primary diagnosis' refers to 'principal diagnosis' for inpatient claims or 'first-listed diagnosis' for outpatient claims.

Etiology/Manifestation Sequencing: When a condition has an underlying cause and manifestations, code the underlying condition first, followed by the manifestation per ICD-10-CM guidelines; manifestation codes may not be acceptable as primary diagnoses.

Sequela of Injury Coding: For late effects (sequela), submit a primary diagnosis for the nature of the sequela and a secondary diagnosis for the original injury with an 'S' in the 7th position.

External Causes: External cause codes (V00–Y99) describe causes of morbidity and are not acceptable as primary/first‑listed diagnoses.

Coding disclaimer: Codes listed in this policy are for reference only and may not be all‑inclusive; deleted or inactive codes at the time of service may not be eligible for reimbursement and listing does not guarantee coverage — coverage is determined by the member benefit document.

Example Codes, Sequencing, and Code List Notes

Example codes and sequencing rulesICD-10

V00-Y99	External causes of morbidity — cannot be primary diagnosis
L62	Nail disorders in diseases classified elsewhere — not a primary diagnosis; code underlying disease first
M24.271	Disorder of ligament, right ankle (example of sequela treatment coding)
S93.411S	Sprain of calcaneofibular ligament, right ankle, sequela (example sequela code with S in 7th position)
K52.1	Toxic gastroenteritis and colitis — code first toxic agent (T51-T65)
Z16.	Resistance to anti-microbial drugs — code infection first

Code list completeness

Scope of code listCodes listed are for reference only and may not be all-inclusive; deleted or inactive codes at time of service may not be eligible for reimbursement.

No coverage guaranteeListing of a code in this policy does not guarantee coverage; coverage is determined by the member benefit document.

Provider responsibilityProviders must use industry standard coding practices; improper billing may result in claim rejection/denial and Molina may recover payments.

MaintenancePolicy and code references may be revised as industry practices change; Molina reserves the right to revise this policy.

Billing, Documentation, and Provider Requirements

Documentation Required

Follow industry coding standards and ICD-10-CM guidelines

Providers and facilities must utilize industry standard coding practices and follow the ICD-10-CM Official Guidelines for Coding and Reporting when submitting claims to Molina. Improper billing or coding may result in Molina rejecting or denying the claim and recovering payment.

Follow ICD-10-CM Official Guidelines for Coding and Reporting.
Use industry standard coding practices for all submissions.
Be aware that Molina may reject/deny claims and recover payments when improper billing/coding is identified.

Key Definitions and Sequencing Rules

Primary diagnosis (definition)

DefinitionThe term 'primary diagnosis' refers to 'principal diagnosis' for inpatient claims or 'first-listed diagnosis' for outpatient claims.

PurposeDetermines which diagnosis is reported as the main condition for claim adjudication.

Reference guidanceFollows ICD-10-CM Official Guidelines for Coding and Reporting as cited in the policy.

Sequela coding

Required codesSequela (late effect) requires two codes: primary code for the nature of the sequela and a secondary code for the original injury with an 'S' in the 7th position.

ExampleM24.271 (disorder of ligament, right ankle) as sequela and S93.411S (sprain of calcaneofibular ligament, right ankle, sequela) as original injury code with 'S' in 7th position.

SequencingSubmit the nature of the sequela as the primary diagnosis and the original injury (with seventh character 'S') as secondary.

Etiology/manifestation sequencing

Sequencing ruleWhen a condition has an underlying cause and manifestations, code the underlying condition first, followed by the manifestation per ICD-10-CM guidelines.

Manifestation codesSome manifestation codes may not be acceptable as primary diagnoses; CMS maintains an Outpatient Code Editor list that is updated quarterly.

ExampleL62 (nail disorders in diseases classified elsewhere) — code the underlying disease first (e.g., M89.4-M89.49); L62 is not a primary diagnosis.