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IMEPro
Impairment Rating
Updated March 2026

Apportionment by Causation

Legal basis: LC §4663

Definition

The method of apportionment based on the actual cause of the disability, as established by the Escobedo and Benson decisions. The physician must determine the approximate percentage of permanent disability caused by the industrial injury versus other factors including genetics, pathology, and non-industrial activities.

Key Facts About Apportionment by Causation in 2026

QME Physicians in CA

~2,500

Evaluation Fee Range

$2,500-$4,000

Report Deadline

30 days

Avg AI-Assisted Turnaround

14 days

Related Terms

Frequently Asked Questions

What is a Apportionment by Causation?

The method of apportionment based on the actual cause of the disability, as established by the Escobedo and Benson decisions. The physician must determine the approximate percentage of permanent disability caused by the industrial injury versus other factors including genetics, pathology, and non-industrial activities.

What is the legal basis for Apportionment by Causation in California workers' compensation?

Apportionment by Causation is governed by LC §4663 under California workers' compensation law. This statute defines the requirements, procedures, and standards for apportionment by causation in the workers' compensation system as of 2026.

How is apportionment by causation calculated in California?

Apportionment by Causation in California workers' compensation is typically determined using the AMA Guides to the Evaluation of Permanent Impairment, 5th Edition (2001). QME and AME physicians use standardized rating methods to ensure consistency across evaluations.