Cal. Lab. Code § 4454
In determining average weekly earnings within the limits fixed in Section 4453, there shall be included overtime and the market value of board, lodging, fuel, and other advantages received by the injured employee as part of his remuneration, which can be estimated in money, but such average weekly earnings shall not include any sum which the employer pays to or for the injured employee to cover any special expenses entailed on the employee by the nature of his employment, nor shall there be included either the cost or the market value of any savings, wage continuation, wage replacement, or stock acquisition program or of any employee benefit programs for which the employer pays or contributes to persons other than the employee or his family.
Ca. Lab. Code § 4454