California Code, Revenue and Taxation Code - RTC § 23642

(a) For each taxable year beginning on or after January 1, 1996, there shall be allowed as a credit against the “tax,” as defined in Section 23036, the amount paid or incurred for eligible access expenditures. The credit shall be allowed in accordance with Section 44 of the Internal Revenue Code,  1 relating to expenditures to provide access to disabled individuals, except that the credit amount specified in subdivision (b) shall be substituted for the credit amount specified in Section 44(a) of the Internal Revenue Code.

(b) The credit amount allowed under this section shall be 50 percent of so much of the eligible access expenditures for the taxable year as do not exceed two hundred fifty dollars ($250).

(c) In the case where the credit allowed by this section exceeds the “tax,” the excess may be carried over to reduce the “tax” in the following year, and succeeding years if necessary, until the credit is exhausted.