(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 Senior Citizen Advocacy Voluntary Tax Contribution Fund established by Section 18731 to be used to conduct the sessions of the California Senior Legislature and to support its ongoing activities on behalf of older persons.

(b) The contribution shall be in full dollar amounts and may be made individually by each signatory on the 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 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.