RTC §18771: (a) Any individual who is allowed the credit under subdivision (c) of Section 17054 may designate on the tax return that a contribution is being made in an amount not to exceed the amount of the credi

(a) Any individual who is allowed the credit under subdivision (c) of Section 17054 may designate on the tax return that a contribution is being made in an amount not to exceed the amount of the credit, without regard to Section 17054.1, which is to be paid to the California Seniors Special Fund. (b) The contribution may be made individually by each eligible signatory on the joint return who is allowed the credit under subdivision (c) of Section 17054. (c) The individual’s return shall be treated as if no designation is made under this article if either of the following apply: (1) The credit allowed by subdivision (c) of Section 17054 reported on the return is insufficient to cover the amount of the contribution. (2) Payments and credits reported on the return, together with any other credits associated with the taxpayer’s return are insufficient to cover the amount of tax owed plus the contribution. (d) A designation under subdivision (a) shall be made for any taxable year on the initial return for that taxable year, and once made shall be irrevocable. (e) The Franchise Tax Board shall revise the forms of the return to allow for the designation permitted under subdivision (a). (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).