Cal. Lab. Code § 4909

Any payment, allowance, or benefit received by the injured employee during the period of his incapacity, or by his dependents in the event of his death, which by the terms of this division was not then due and payable or when there is any dispute or question concerning the right to compensation, shall not, in the absence of any agreement, be an admission of liability for compensation on the part of the employer, but any such payment, allowance, or benefit may be taken into account by the appeals board in fixing the amount of the compensation to be paid. The acceptance of any such payment, allowance, or benefit shall not operate as a waiver of any right or claim which the employee or his dependents has against the employer.