Rev. & Tax. Code, § 60202

(a) Each interstate user shall prepare and file with the board a return in the form as prescribed by the board, which may include, but not be limited to, electronic media showing the amount of diesel fuel used during the quarterly reporting period by the interstate user in this state, the amount of any tax due, and any other information as the board may require for the administration of this part. The return shall be filed with the board on or before the last day of the calendar month following the close of the quarterly period to which it relates, together with a remittance payable to the board of the amount of tax due. To facilitate the administration of this part, the board may require the filing of returns for other than quarterly periods. Returns shall be authenticated in a form or pursuant to methods as may be prescribed by the board.

(b) An interstate user subject to the tax imposed by Section 60115 shall be allowed a credit against the amount of tax due on his or her return for an amount equal to the tax imposed by Section 60115 on diesel fuel purchased in this state in that same return period for use in the operation of a qualified motor vehicle. No credit shall be allowed unless the tax imposed by Section 60050 and the taxes imposed by Part 1 (commencing with Section 6001) and Part 1.5 (commencing with Section 7200) of Division 2 of the Revenue and Taxation Code and Section 35 of Article XIII of the California Constitution have been paid upon the purchase of the diesel fuel by the interstate user to a diesel vendor in this state. When the amount of the credit for any return period exceeds the amount of tax due for the return period, the excess shall be allowed as a credit against the amount of tax due for succeeding reporting periods or shall be refunded.

(c) Credits and refunds allowed pursuant to subdivision (b) shall be charged against the Motor Vehicle Fuel Account to the extent the total amount of credits and refunds allowed to all taxpayers for the fiscal year does not exceed the combined amounts due under subdivisions (a) and (b) of Section 60115. To the extent the total amount of credits and refunds allowed to all taxpayers for the fiscal year pursuant to subdivision (b) exceeds the combined amounts due under subdivisions (a) and (b) of Section 60115, the credits and refunds shall be charged against the Motor Vehicle Fuel Account as to the amount of the credits and refunds established under subdivision (a) of Section 60115 and shall be charged against the Retail Sales Tax Fund as to the amount of the credits and refunds established under subdivision (b) of Section 60115.