California Code, Revenue and Taxation Code - RTC § 17734

For purposes of computing “taxable income of a nonresident or part-year resident” under paragraph (1) of subdivision (i) of Section 17041, in the case of a nonresident beneficiary, income and deduction derived through an estate or trust shall be included in that computation only to the extent that the income or deduction is derived by the estate or trust from sources within this state.