Cal. Bus. & Prof. Code § 21663
(a) Except as provided in Section 21663.1, every vendor shall report all merchandise offered or displayed for sale or exchange on a form, prescribed or approved by the California Department of Justice, containing all the following information:
(10) A requirement that the vendor check an appropriate box that sets forth his or her permit number for sales tax purposes.
If the vendor’s permit number is not listed in the appropriate place on the form, the vendor shall indicate that he or she has not and does not contemplate making more than two sales of sufficient size, scope, and character within a 12-month period to require a permit.