Cal. Rev. & Tax. Code § 18810

(a) Any individual may designate on the tax return that a contribution in excess of the tax liability, if any, be made to the California Veterans Homes Fund established by Section 1051 of the Military and Veterans Code. 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 shall be made for any taxable year on the initial 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. If no designee is specified, the contribution shall be transferred to the General Fund after reimbursement of the direct actual costs of the Franchise Tax Board for the collection and administration of funds under this article.
(d) The Franchise Tax Board shall revise the form of the return to include a space labeled the “California Veterans Homes 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 for veterans homes operations.
(e) Notwithstanding any other law, a voluntary contribution designation for the California Veterans Homes Fund may not be added on the tax return until another voluntary contribution designation is removed.
(f) 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).