California Code, Revenue and Taxation Code - RTC § 19058

(1) In the case of a trade or business, the term “gross income” means the total of the amounts received or accrued from the sale of goods or services (if the amounts are required to be shown on the return) prior to diminution by the cost of the sales or service.

(2) In determining the amount omitted from gross income, there shall not be taken into account any amount which is omitted from gross income stated in the return if the amount is disclosed in the return, or in a statement attached to the return, in a manner adequate to apprise the Franchise Tax Board of the nature and amount of the item.