"Can I work somewhere else while I'm on comp?"

The rule

Temporary disability replaces lost earning capacity. If you are earning, that changes what is owed. Temporary partial disability exists precisely for this — where you are working reduced hours or lower-paid work, a partial benefit covers part of the difference.

So working is not prohibited. Concealing it is the problem.

What has to be true

The work has to be within your medical restrictions. All of them. Doing something at a second job that your restrictions prohibit is the fact pattern that produces a fraud referral, and it does not matter that you needed the money.

The earnings have to be reported — to the claims administrator, in writing, as they occur. Not at the end. Not when asked.

And the work has to be consistent with what you have told your doctor. If you tell the evaluator you cannot stand for more than twenty minutes and you are working a shift on your feet, those two things are going to meet each other in a deposition.

The second job you already had

Different situation, and an important one. If you were already working two jobs when you were injured, the earnings from both belong in your average weekly wage under Labor Code § 4453(c). Adjusters routinely compute the rate from one employer's payroll alone, and that single omission is one of the most common underpayments in the system.

And if the injury prevents you from doing the second job too, that loss is part of the claim. I have two jobs.

Self-employment and side work

Same rules, and more scrutiny. Driving, delivery, contracting, selling online, helping at a family business — all of it counts as work, whether or not anyone issued a paycheck, and all of it is discoverable.

"I wasn't getting paid" is not the safe answer people think it is, because the argument being made is about your physical capacity, not your income.