"I didn't report it right away."

The 30-day rule, and the exception that swallows it

Labor Code § 5400 requires notice to the employer within 30 days.

Labor Code § 5402(a) then provides that knowledge of an injury "obtained from any source, on the part of an employer, the employer's managing agent, superintendent, foreman, or other person in authority" is equivalent to formal notice.

So: a supervisor who watched it happen is notice. A foreman you told at the time is notice. A first-aid log entry, an incident report, a text message to a manager — all notice.

And even where notice was genuinely late, § 5403 provides that late notice does not bar the claim unless the employer was actually prejudiced by it. That is a real burden on the employer, not a technicality that ends your case.

More valid California claims die from a worker assuming they missed a deadline than from actually missing one.

If your injury developed over time

This changes everything. For a cumulative trauma or occupational disease claim, Labor Code § 5412 sets the date of injury as the date you first suffered disability and knew, or reasonably should have known, it was work-related.

Both are required. Exposure alone is not a date of injury. A diagnosis alone is not a date of injury.

So a worker whose back wore out over fifteen years, who kept working through it, and who was first taken off work last month, may well have a date of injury of last month — regardless of when the wear began.

The deadlines that do matter

In every one of these, the "date of injury" for a gradual condition is the § 5412 date — not the date the wear started.

What to do now

Report it in writing today, however late it feels. Text or email, dated.

File the DWC-1. Do not wait to be given one.

Write down who knew, and when — every supervisor who saw it, every coworker you told, every time you mentioned it.

Get the medical records that show when you first sought care for it, including anything paid through your own health insurance.

And do not decide on your own that you are out of time. That determination requires the § 5412 analysis, and it is free to have someone run it.