Cal. Rev. & Tax. Code § 7277

(a) In the event that any tax collected under this part is determined on the basis of Section 4 of Article XIII A of the California Constitution to be unconstitutional in a final and nonappealable decision of a court of competent jurisdiction, and the revenues derived from the unconstitutional tax are held by the board in an impound account, a person who has reimbursed a retailer for that payment of that tax or a person, other than in a capacity as a retailer, who has paid that tax may file with the board a claim for refund of the unconstitutional tax in accordance with the requirements and procedures set forth in subdivision (b).
(b)
1. (1) The claim for refund shall be in writing, shall state the specific ground upon which the claim is founded, and shall be accompanied by proof of payment of the tax to a retailer or wholesaler, including, but not limited to, a copy of an invoice, bill of sale, or purchase contract, that indicates the following:
  1. (A) The date upon which, and place at which, the purchase occurred.
  2. (B) A description of the property purchased.
  3. (C) The price paid for the property.
  4. (D) The amount of the transactions and use tax collected with respect to the purchase, or if that amount is not separately stated, the amount of the purchase and the rate of tax from which the amount of transactions and use tax may be calculated.
2. (2) In the case of a purchaser that has self-reported use tax to the state, the claim for refund shall also indicate the amount of use tax paid and the period for which those taxes were remitted.
3. (3)
  1. (A) Only a claim for refund made with respect to a single purchase or aggregate purchases of five thousand dollars ($5,000) or more shall be eligible for refund pursuant to this section.
  2. (B) A claim for refund shall be filed within one year of the first day of the first calendar quarter commencing after the effective date of this section or after the date upon which the court decision described in subdivision (a) becomes final and nonappealable, whichever occurs later. If that one-year period does not end on the last day of a calendar quarter, it shall end on the last day of the preceding calendar quarter or on the last day of the calendar quarter which is nearest to the date the one-year period ends.
(c) For purposes of this section, “purchaser” means any person or entity, other than in a capacity as a retailer, who purchased tangible personal property the sale or use of which was subject to the unconstitutional tax described in subdivision (a).
(d) Interest shall be paid on the refunds provided by this chapter pursuant to Section 6907.