California Labor Code § 4663 Statutory Text:
(a) Apportionment of permanent disability shall be based on causation.
(b) A physician shall make an apportionment determination by finding what approximate percentage of the permanent disability was caused by the direct result of injury arising out of and occurring in the course of employment and what approximate percentage of the permanent disability was caused by other factors both before and subsequent to the industrial injury, including prior industrial injuries.
(c) In order for a physician’s report to be complete on the issue of permanent disability, it must include an apportionment determination. A report that does not include an apportionment determination may be returned to the physician for correction.
(d) An employee who claims an industrial injury shall, upon request, disclose all previous permanent disabilities or physical impairments.
Understanding Labor Code §4663 – Apportionment of Permanent Disability in California
When you file a workers’ compensation claim in California, your right to permanent disability (PD) benefits hinges on how much of your disability was caused by your work injury—and how much was caused by other, non-work-related factors. This is where Labor Code §4663 comes into play.
What Is Apportionment?
Apportionment refers to the process of dividing responsibility for a permanent disability between different causes. Under §4663, doctors must allocate percentages of your disability between:
- Your current work injury, and
- Other factors, including:
- Pre-existing conditions
- Prior injuries
- Age-related degeneration
- Lifestyle factors or non-work accidents
The idea is to only compensate injured workers for the portion of disability directly caused by their job.
The Doctor’s Role in Apportionment
When you reach maximum medical improvement (MMI), your evaluating physician (QME, AME, or PTP) must provide a report that includes:
- The total extent of your permanent disability, and
- An apportionment determination—i.e., what percentage was caused by your industrial injury versus non-industrial factors.
If the doctor doesn’t include this, the report is incomplete and will be returned for correction under §4663(c).
Example of How Apportionment Works
Suppose you injured your back at work lifting heavy equipment, but you also had a pre-existing back condition from a car accident 10 years ago. The doctor might determine that:
- 60% of your disability is due to the work injury
- 40% is due to the old car accident
That means your permanent disability benefits will be calculated based on 60% of the total disability, not the full amount.
Disclosure Requirement for Employees
Under §4663(d), if you’re claiming an industrial injury, you must disclose prior permanent disabilities or impairments if asked. Failing to do so may undermine your credibility and affect the outcome of your case.
Common Issues in Apportionment Cases
Apportionment is one of the most contested issues in workers’ compensation. Employers and insurers often push for greater apportionment to non-work factors to reduce payouts, while injured workers want to ensure that their disability is properly attributed to their job injury.
Some common disputes include:
- Whether the doctor’s apportionment opinion is based on substantial medical evidence
- Disagreements over what counts as a pre-existing condition
- Attempts by employers to blame natural aging or unrelated conditions
That’s why it’s critical to have a skilled legal team who can challenge improper apportionment.
How EFLL Can Help
At Employees First Labor Law, we fight to make sure our clients get every dollar they’re entitled to—and that means challenging unfair apportionment findings. If your doctor’s report is incomplete, biased, or unsupported by medical evidence, we’ll work to correct it.
We know the tricks insurance companies use. Don’t leave your future in their hands.
Get the Help You Deserve
If you’re facing issues with apportionment of permanent disability under Labor Code §4663, contact EFLL today for a free consultation. Let us protect your rights and your benefits.
📚 Learn More
Want to understand more key protections under California law? Check out our full guide:
👉 Top 25 California Labor Codes for Workers’ Comp
Contact Employees First Labor Law to make sure your medical rights are protected and your recovery isn’t compromised.
