California Code, Revenue and Taxation Code - RTC § 18749

(a) An individual may designate on the tax return that a contribution in excess of the tax liability, if any, be made to the Native California Wildlife Rehabilitation Voluntary Tax Contribution Fund, established by Section 18749.1. That designation is to be used as a voluntary checkoff 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 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 though 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) If an individual designates a contribution to more than one account or fund listed on the tax return, and the amount available for designation is insufficient to satisfy the total amount designated, the contribution shall be allocated among the designees on a pro rata basis.

(e) When another voluntary contribution designation is removed from the tax return, or as soon as space is available, whichever occurs first, the Franchise Tax Board shall revise the form of the tax return to include a space labeled the “Native California Wildlife Rehabilitation Voluntary Tax Contribution Fund” to allow for the designation provided. The form shall include in the instruction information that the contribution may be in the amount of one dollar ($1) or more and that the contribution shall be used to support the rehabilitation of injured, sick, or orphaned native wildlife and for wildlife conservation education.

(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).