California Code, Government Code - GOV § 89517

(a) Campaign funds shall not be used for payment or reimbursement for the lease of real property or for the purchase, lease, or refurbishment of any appliance or equipment, where the lessee or sublessor is, or the legal title resides, in whole or in part, in a candidate, elected officer, campaign treasurer, or any individual or individuals with authority to approve the expenditure of campaign funds, or an immediate family member of one of those individuals.

(b) Campaign funds shall not be used to purchase real property.  Except as prohibited by subdivision (a), campaign funds may be used to lease real property for up to one year at a time where the use of that property is directly related to political, legislative, or governmental purposes.

(c) For the purposes of this section, real property, appliance, or equipment is considered to be directly related to a political, legislative, or governmental purpose as long as its use for other purposes is only incidental to its use for political, legislative, or governmental purposes.