Apportionment

What apportionment is

Apportionment is the allocation of permanent disability by cause. California apportions on causation: the employer is liable only for the percentage of permanent disability directly caused by the injury arising out of and in the course of employment (Labor Code sections 4663 and 4664).

The rule

A physician who reports on permanent disability must address causation and must include an apportionment determination for the report to be complete. The doctor states what approximate percentage was caused by the industrial injury and what percentage by other factors before and after it, including prior industrial injuries, or explains why they cannot (Labor Code section 4663(c)). An employee must disclose prior permanent disabilities on request. If the worker received a prior PD award, the law conclusively presumes that disability still exists at the time of the new injury (Labor Code section 4664(b)), and total PD awards for one body region are capped at 100 percent over a lifetime.

Why it matters to an applicant firm

Apportionment is often the biggest swing factor in a WC case's value. Defense counsel ask the QME or AME to apportion to degeneration, prior injuries or non-industrial conditions. Applicant firms review the report for whether the apportionment is substantial medical evidence: explained, based on the right legal standard, and not a bare guess. Prior awards, prior claims and prior treatment records belong in the file early, because they surface at the evaluation anyway. See the PD rating guide and the cumulative trauma guide.