Cal. Rev. & Tax. Code § 18914

(a) An individual may designate on the tax return that a contribution in excess of the personal income tax liability, if any, be made to the Suicide Prevention Voluntary Tax Contribution Fund established by Section 18915. That designation is to be used as a voluntary contribution on the tax return.
(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 any taxable year on the original return for that taxable year and once made is irrevocable. If payments and credits reported on the return, together with any other credits associated with the taxpayer’s account, do not exceed the taxpayer’s liability, the return shall be treated as if no designation has been made.
(d) When another voluntary contribution designation is removed from the tax return, or as soon as space is available, the Franchise Tax Board shall revise the form of the return to include a space labeled the “Suicide Prevention Voluntary Tax Contribution Fund” to allow for the designation permitted. 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 support crisis centers located in the state that are active members of the National Suicide Prevention Lifeline, with priority given to those crisis centers located in rural and desert communities.
(e) A deduction shall be allowed under Article 6 (commencing with Section 17201) of Chapter 3 of Part 10 for any contribution made pursuant to subdivision (a).