California Code, Revenue and Taxation Code - RTC § 4911

(a) If an assessee or agent of the assessee, by mistake, pays the tax on other than the property intended and by substantial evidence convinces the tax collector that the payment was intended for another property, the tax collector shall cancel the credit on the unintended property and transfer the payment to the property intended as prescribed in this article at any time before a guaranty or certificate of title issues respecting the unintended property and before two years have elapsed since the date of payment.

(b) If through no fault of the assessee or agent of the assessee, a tax payment is credited to property other than the property intended and the taxpayer by substantial evidence convinces the tax collector that the payment should have been credited to another property, the tax collector shall cancel the credit on the unintended property and transfer the payment to the property intended as prescribed in this article at any time before a guaranty or certificate of title issues respecting the unintended property and before two years have elapsed since the date of the payment.

(c) If any person mistakenly pays an amount of tax and there is no property of that person in the county to which that payment properly applies, the tax collector shall, by being convinced upon substantial evidence that the payment was a mistake, cancel the payment and return the amount paid to that person, as prescribed in this article at any time before a guaranty or certificate of title issues respecting the unintended property and before two years have elapsed since the date of the payment.

(d) The county shall transfer a payment pursuant to subdivision (a) or return a payment pursuant to subdivision (c) within 60 days of the later of the date of the county verifying that the payment was paid by mistake or the date the payment is not subject to chargeback, dishonor, or reversal, or shall pay interest as prescribed in subdivision (e).

(e) If a refund to an assessee or agent of the assessee is created as a result of subdivision (a) or (c), interest as prescribed by Section 5151 shall not be paid. However, if the refund was not issued within 60 days of the county verification of the refund or credit due, interest shall be paid from the date of verification.