Cal. Rev. & Tax. Code § 30361.5

When an amount represented by a person to a customer as constituting reimbursement for taxes upon the distribution of tobacco products pursuant to this part is computed upon an amount that is not taxable or is in excess of the tax amount and is actually paid by the customer to the person, the amount so paid shall be returned by the person to the customer upon notification by the State Board of Equalization or the customer that an excess has been ascertained. If the person fails or refuses to do so, the amount so paid, if knowingly or mistakenly computed by the person upon an amount that is not subject to the tax imposed by this part or that is in excess of the tax amount, shall be remitted by that person to this state. Those amounts remitted to the state by the person shall be credited by the board to any amounts due and payable from that customer that are subject to this part and that are based on the same activity, and the balance, if any, shall constitute an obligation due from the person to this state.