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What Is California Labor Code §4660: Permanent Disability Rating?
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By Eman Yazdchi, Esq. · Certified Specialist in Workers' Compensation Law, State Bar of California Board of Legal Specialization · Cal Bar #285231
(a) In determining the percentages of permanent disability, account shall be taken of the nature of the physical injury or disfigurement, the occupation of the injured employee, and his or her age at the time of the injury, consideration being given to an employee's diminished future earning capacity.
How is permanent disability calculated under Labor Code 4660?
Labor Code 4660 builds a PD rating in four steps: an AMA Guides Fifth Edition WPI percentage, an occupation adjustment, an age adjustment, and conversion to weeks of indemnity under Labor Code 4658.
Labor Code 4660 turns a work injury into a dollar amount. The process has four steps. First, a medical evaluator assigns a Whole Person Impairment percentage using the AMA Guides Fifth Edition. Second, the percentage is adjusted for occupation. Third, an age adjustment is applied. Fourth, the result converts to weeks of indemnity under Labor Code 4658.
Eman Yazdchi is a Certified Specialist in workers' compensation law, certified by the California Board of Legal Specialization, State Bar of California. He audits the rating calculation on every PD file at Yazdchi Law.
What is the AMA Guides Fifth Edition used in California PD ratings?
The AMA Guides Fifth Edition is the medical rulebook for assigning a Whole Person Impairment percentage. California uses the Fifth Edition. The Sixth Edition is not adopted here.
The Fifth Edition sets the WPI starting point. A lumbar disc herniation without surgery typically rates between 7 and 13 percent WPI. A single-level spinal fusion typically rates around 25 to 28 percent. Those percentages then go through occupation and age adjustments. The WPI is the raw input, not the final rating.
How does the occupation adjustment work under Labor Code 4660?
The occupation adjustment increases or decreases the base WPI based on how much the injured body part affects the worker's specific job duties and earning capacity over time.
Two workers with the same fusion can get different ratings. A warehouse worker with a back fusion gets a larger occupation adjustment than a desk worker. The warehouse job depends more on a healthy lumbar spine. That difference is built into the Permanent Disability Rating Schedule. Occupation is one reason why two identical diagnoses produce different settlement values.
How does Labor Code 4660 interact with Labor Code 4663 apportionment?
After the Labor Code 4660 rating is set, the insurer may argue apportionment under Labor Code 4663. A successful apportionment claim reduces the PD award by the non-industrial percentage.
The Labor Code 4660 rating is the baseline. If the insurer claims 30% non-industrial apportionment under Labor Code 4663, the award falls by 30%. The employer bears the burden of proving apportionment. Prior imaging findings alone, without symptoms or prior treatment, are a weak basis for that argument.
How does the Labor Code 4660 rating convert to actual dollars?
The PD percentage converts to weeks of indemnity under Labor Code 4658. Higher percentages earn more weeks. Ratings above 70 percent trigger a lifetime pension component under Labor Code 4659.
A 30% rating produces about 86 weeks of PD indemnity. A 70% rating produces several hundred weeks plus a lifetime pension. The weekly rate is based on the worker's average weekly wage at the time of injury. It is subject to the annual statutory maximum. A 40% rating in California commonly reaches tens of thousands of dollars in total indemnity.
Related: California settlement pillar · Labor Code 4663 explainer.
Injured at work? Call (661) 273-1780
Tap to call →Eman Yazdchi is a Certified Specialist in workers' compensation law, certified by the California Board of Legal Specialization, State Bar of California. Yazdchi Law serves injured workers throughout Greater Los Angeles. We appear at the WCAB in Van Nuys, Los Angeles, Long Beach, Pomona, San Bernardino, Riverside, and Oxnard. Call (661) 273-1780 for a free case review.
Frequently Asked Questions
Can an injured worker dispute the WPI percentage assigned by the QME?
Yes. Under Labor Code 4660, the evaluator's WPI percentage can be challenged. The worker's attorney can cross-examine the QME on their Guides methodology. An AME can provide a different WPI opinion. The WCAB judge weighs the competing opinions and decides which is better supported by the medical record.
Does Labor Code 4660 apply to both specific injuries and cumulative trauma?
Yes. Labor Code 4660 applies to all types of industrial injuries. It covers specific traumatic injuries and cumulative trauma alike. The medical evaluator uses the AMA Guides Fifth Edition to rate any qualifying permanent impairment. The occupation and age adjustments apply the same way regardless of injury type.
How does the age adjustment under Labor Code 4660 work?
The age adjustment modifies the base rating based on the worker's age at the time of injury. Older workers typically receive an upward adjustment. Younger workers may receive a downward adjustment. The factor reflects the long-term impact of the disability on earning capacity over the remaining years of employment.
What body parts does the AMA Guides Fifth Edition cover for California ratings?
The AMA Guides Fifth Edition covers every major body system. This includes the spine, upper extremities, lower extremities, pulmonary system, cardiovascular system, and mental health under Labor Code 3208.3. California has used the Fifth Edition since the 2004 reform. The WCAB applies it in every permanent disability case.
Can a low WPI percentage still result in a significant PD award?
Yes. A 10 percent WPI, once adjusted for occupation and age, can convert to a meaningful PD percentage. Workers in physically demanding jobs receive larger occupation adjustments. Those adjustments can push a modest WPI into a PD percentage that generates tens of thousands of dollars in indemnity under Labor Code 4658.
Last reviewed by Eman Yazdchi, Esq., July 2026.
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