Every other impairment in the schedule starts from anatomy — degrees of motion, strength, organ function. Psych starts from a single number describing how a person functions: the GAF score. That makes psychiatric ratings both the most mechanical conversion in the book and the most contested input in the case. This guide covers both halves.
From GAF to WPI
The GAF — Global Assessment of Functioning — is a 1–100 clinician rating of overall psychological functioning. The 2005 PDRS (page 1-16) converts it directly to whole-person impairment: 70 and above is no ratable impairment, and WPI climbs as the score falls:
45 → 40 · 40 → 51 · 35 → 61 · 30 → 70% WPI
Notice the curve steepens through the middle: from GAF 60 to 40, every GAF point is worth roughly 1.8 points of WPI. Small disagreements between evaluators are amplified — which is why the GAF number itself, not the conversion, is where psych cases are fought.
Then it’s a normal rating
The converted WPI enters the pipeline as impairment number 14.01.00.00 and runs like any other rating — 1.4 adjustment, occupation, age. Here is GAF 50 (the “moderate/serious” boundary), age 40, 2024 injury at the maximum rate, in two jobs:
279.25 weeks · $80,982.50
194.00 weeks · $56,260
Read the variants: this is the mirror image of the back-injury pair. There, heavy labor rated double the clerk; here the clerk rates 12 points and $24,722.50 higher, because the schedule treats concentration, judgment, and interpersonal function as the tools of clerical work. Occupational variants cut whichever way the job actually depends on the impaired function.
The 2013 bar — §4660.1(c)
For injuries on or after January 1, 2013, SB 863 drew a hard line through psych add-ons: no increased PD for a psychiatric disorder (or sleep or sexual dysfunction) arising out of a compensable physical injury. Two statutory exceptions restore the add-on: the worker was a victim of a violent act or directly exposed to a significant violent act, or the underlying injury is catastrophic. Three things the bar does not touch: a direct psychiatric injury (where the psyche is the injury — a robbery, a workplace assault, witnessed trauma), medical treatment for the psychiatric condition, and temporary disability. The calculator flags the bar when you add a psych row to a post-2013 physical-injury case; whether an exception applies is a legal call that stays with you.
Where the disputes live
The GAF itself. Two qualified evaluators can defensibly land ten points apart, and ten points can be twenty points of WPI — this is why psych cases so often turn on the choice of evaluator. Compensability gates. A psychiatric claim generally requires six months of employment (Lab. Code §3208.3(d), with an exception for sudden and extraordinary events), actual events of employment as the predominant cause, and survives a good-faith-personnel-action defense (§3208.3(h)) — all before rating even begins. Apportionment to non-industrial life stressors is near-universal in psych reports and works like any other apportionment.
Check it yourself
The calculator has a GAF mode for the psych impairment: type the score and it applies the page 1-16 conversion, the era’s adjustment, and your occupation and age — the full string, live. Every figure above was computed by that engine, and every term is defined in the glossary.