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✦ Certified Specialist in Workers’ Compensation Law — Certified by the State Bar of California, Board of Legal Specialization ✦
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By Eman Yazdchi, Esq. · Certified Specialist in Workers' Compensation Law, State Bar of California Board of Legal Specialization
In California, Labor Code §5412 is the discovery rule for cumulative-trauma and occupational-disease claims — the date of injury is when the worker first suffered disability AND knew (or should have known) the disability was work-related. The §5412 date controls when the §5405 one-year filing window begins. Yazdchi Law handles California CT and discovery disputes statewide.
California Labor Code §5412 sets the date of injury for California occupational-disease and cumulative-trauma claims as the date the employee first suffered disability AND knew (or with reasonable diligence should have known) the disability was caused by the employment. The §5412 statute applies the "discovery rule" — for slow-developing injuries with no single accident date, California fixes the date of injury based on when the worker reasonably connected the disability to the work, not when exposure began.
Under California Labor Code §5412, California cumulative-trauma claims under California Labor Code §3208.1 (repetitive motion, prolonged standing, computer use developing into a back, shoulder, or wrist injury) and occupational-disease claims (silicosis, asbestos exposure, chemical sensitization) often have no single accident date. The §5412 discovery rule fixes the California date of injury at the moment of disability-plus-knowledge, which is the trigger for the California Labor Code §5405 one-year statute of limitations to file a claim.
Under California Labor Code §5405, a California injured worker generally has one year from the date of injury to file a claim. For a CT or occupational-disease case, the California Labor Code §5412 date controls when that one-year clock starts. A California worker who suffered slow-developing back pain over a decade of warehouse lifting does not have the §5405 clock running from the first day of lifting — it runs from the §5412 date when the worker first suffered disability AND knew the work caused it.
Under California Labor Code §5412, the California §5412 date of injury requires BOTH disability AND knowledge of work causation. Disability means the worker became unable to perform regular work — typically when a treating physician took the worker off duty, imposed restrictions, or the worker missed time. Knowledge means the worker actually knew (or with reasonable diligence should have known) the disability was caused by the employment. Both elements must be present; the §5412 date is the later of the two.
Under California Labor Code §5412 (date of injury) and California Labor Code §5500.5 (which employer is liable for a California cumulative-trauma claim), the §5412 date triggers the §5500.5 lookback. California Labor Code §5500.5 places California CT liability on the last year of injurious exposure preceding the §5412 date. A worker who developed a CT shoulder injury across three California employers is generally a §5500.5 claim against the final employer during that final year of exposure.
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Tap to call →Last reviewed by Eman Yazdchi, Esq., May 2026.
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