Cal. RTC § 18895

(a) An individual may designate on the tax return that a contribution in excess of the tax liability, if any, be made to the School Supplies for Homeless Children Voluntary Tax Contribution Fund established by Section 18896.

(b) The contributions shall be in full dollar amounts and may be made individually by each signatory on a joint return.

(c) A designation under subdivision (a) shall be made for a taxable year on the original return for that taxable year, and once made shall be irrevocable. If payments and credits reported on the return, together with any other credits associated with the individual’s account, do not exceed the individual’s tax liability, the return shall be treated as though no designation has been made.

(d) If an individual designates a contribution to more than one account or fund listed on the tax return, and the amount available is insufficient to satisfy the total amount designated, the contribution shall be allocated among the designees on a pro rata basis.

(e) The Franchise Tax Board shall revise the form of the return to include a space labeled “School Supplies for Homeless Children Voluntary Tax Contribution Fund” to allow for the designation permitted under subdivision (a). The form shall also include in the instructions information that the contribution may be in the amount of one dollar ($1) or more and that the contribution shall be used to provide school supplies for homeless children.

(f) Notwithstanding any other law, a voluntary contribution designation for the School Supplies for Homeless Children Voluntary Tax Contribution Fund shall not be added on the tax return until another voluntary contribution designation is removed.

(g) A deduction shall be allowed under Article 6 (commencing with Section 17201) of Chapter 3 of Part 10 for a contribution made pursuant to subdivision (a).