Cal. PROB § 16371

(a) Except to the extent that Article 3 (commencing with Section 16330) applies for a beneficiary that is a trust, each beneficiary described in subdivision (f) of Section 16370 is entitled to receive a share of the net income equal to the beneficiary’s fractional interest in undistributed principal assets, using values as of the distribution date. If a fiduciary makes more than one distribution of assets to beneficiaries to which this section applies, each beneficiary, including a beneficiary that does not receive part of the distribution, is entitled, as of each distribution date, to a share of the net income the fiduciary received after the decedent’s death, an income interest’s other terminating event, or the preceding distribution by the fiduciary.

(b) In determining a beneficiary’s share of net income under subdivision (a), the following rules apply:

(1) The beneficiary is entitled to receive a share of the net income equal to the beneficiary’s fractional interest in the undistributed principal assets immediately before the distribution date.

(2) The beneficiary’s fractional interest under paragraph (1) shall be calculated on the aggregate value of the assets as of the distribution date without reducing the value by any unpaid principal obligation, and without regard to either of the following:

(A) Property specifically given to a beneficiary under the decedent’s will or the terms of the trust.

(B) Property required to pay pecuniary amounts not in trust.

(3) The distribution date under paragraph (1) may be the date as of which the fiduciary calculates the value of the assets, if that date is reasonably near the date on which the assets are distributed.

(c) To the extent a fiduciary does not distribute under this section all the collected but undistributed net income to each beneficiary as of a distribution date, the fiduciary shall maintain records showing the interest of each beneficiary in the net income.

(d) If this section applies to income from an asset, a fiduciary may apply the rules in this section to net gain or loss realized from the disposition of the asset after the decedent’s death, an income interest’s terminating event, or the preceding distribution by the fiduciary.