Generally, a "return" includes, but is not limited to all returns required by Section 13501 of the Revenue and Taxation Code, all amended returns required by Section 13503, and the notice required by Section 13504.
Cal. Code Regs. Tit. 2, § 1138.50
Note: Authority cited: Section 14103, Revenue and Taxation Code. Reference: Sections 13501, 13503, 13504 & 13516, Revenue and Taxation Code.