The thirty-day notice requirement
Cal. Lab. Code § 5400 generally requires notice of injury to the employer within thirty days. For a specific injury the trigger is obvious. For cumulative trauma it connects to the § 5412 date of injury.
In practice this deadline is more forgiving than it sounds, because the statutory scheme provides that failure to give notice is not necessarily a bar where the employer had actual knowledge or was not prejudiced by the delay.
But relying on that is unnecessary. A dated email to a supervisor or HR costs nothing and eliminates the argument entirely. The workers who run into trouble are the ones who mentioned it in a hallway and cannot establish when.
The claim form, and why filing is different from reporting
Cal. Lab. Code § 5401 requires the employer to provide a DWC-1 claim form within one working day of learning of an injury. That is the employer's obligation.
It is also the obligation most frequently ignored, and workers who never receive a form often assume nothing more is required of them because they told someone.
Reporting and filing are different acts. Reporting starts the employer's duty. Filing the DWC-1 starts the carrier's ninety-day clock under § 5402 and creates the record that the claim exists.
If you were never given a form, the form is available from the Division of Workers' Compensation and you can complete and submit it yourself. Keep a dated copy of what you submitted and how.
The ninety-day presumption is a real advantage
Cal. Lab. Code § 5402 provides that if liability is not rejected within ninety days of the date the claim form is filed, the injury is presumed compensable.
That presumption can generally be rebutted only by evidence discovered after the ninety-day period. It exists because carriers were leaving claims unresolved indefinitely while injured workers went without treatment.
The practical significance is that the date you file the DWC-1 matters enormously and is entirely within your control. A claim reported in March and filed in July has a ninety-day clock starting in July, not March.
§ 5402 also generally requires the employer to authorize medical treatment up to a statutory limit while the claim is being investigated, so treatment does not have to wait for a decision.
Cumulative trauma timing, and why old injuries are often still live
This is the provision that changes outcomes most often. § 5412 defines the date of injury for a cumulative injury as the date the employee first suffered disability and either knew, or in the exercise of reasonable diligence should have known, that the disability was caused by present or prior employment.
Both elements are required. Symptoms alone are not disability. And knowledge means knowing the work connection, which frequently arrives only when a physician says so for the first time.
So a worker who has managed wrist pain for five years, never missed a day, never had restrictions and was never told it was occupational may have a date of injury measured in months rather than years.
This is highly fact-specific and it is the single best reason not to assume a claim is dead without asking. The assumption costs people valid claims constantly.
After the claim resolves
Resolution is not always permanent. Where a condition worsens after a claim is resolved, California generally allows a petition to reopen for new and further disability within five years of the date of injury.
That window is measured from the date of injury, not from the settlement, which means a claim resolved in year four leaves roughly a year of reopening availability.
How a claim is resolved also matters. Different settlement structures treat future medical care differently, and the choice affects what happens if the condition deteriorates.
It is worth understanding those differences before agreeing to any resolution, because the structure is not something that can be revisited afterward.
