(b) An asset becomes subject to a trust at the following times:
     (1) In the case of an asset that is transferred to a trust during the transferor's life, on the date it is transferred to the trust.
     (2) In the case of an asset that becomes subject to a trust by reason of a will, even if there is an intervening period of administration of the testator's estate, on the date of the testator' s death.
     (3) In the case of an asset that is transferred to a fiduciary by a third party because of the individual's death, on the date of the individual's death.
     (c) An asset becomes subject to a successive income interest on the day after the preceding income interest ends, as determined under subdivision (d), even if there is an intervening period of administration to wind up the preceding income interest.
     (d) An income interest ends on the day before an income beneficiary dies, or another terminating event occurs, or on the last day of a period during which there is no beneficiary to whom a trustee may distribute income.

16346. (a) A trustee shall allocate an income receipt or disbursement other than one to which subdivision (a) of Section 16340 applies to principal if its due date occurs before a decedent dies in the case of an estate or before an income interest begins in the case of a trust or successive income interest.
     (b) A trustee shall allocate an income receipt or disbursement to income if its due date occurs on or after the date on which a decedent dies or an income interest begins and it is a periodic due date. An income receipt or disbursement shall be treated as accruing from day to day if its due date is not periodic or it has no due date. The portion of the receipt or disbursement accruing before the date on which a decedent dies or an income interest begins shall be allocated to principal and the balance shall be allocated to income.
     (c) An item of income or an obligation is due on the date the payer is required to make a payment. If a payment date is not stated, there is no due date for the purposes of this chapter. Distributions to shareholders or other owners from an entity to which Section 16350 applies are deemed to be due on the date fixed by the entity for determining who is entitled to receive the distribution or, if no date is fixed, on the declaration date for the distribution. A due date is periodic for receipts or disbursements that must be paid at regular intervals under a lease or an obligation to pay interest or if an entity customarily makes distributions at regular intervals.

16347. (a) For the purposes of this section, "undistributed income" means net income received before the date on which an income interest ends. The term does not include an item of income or expense that is due or accrued or net income that has been added or is required to be added to principal by the trust.
     (b) Except as provided in subdivision (c), on the date when a mandatory income interest ends, the trustee shall pay to a mandatory income beneficiary who survives that date, or to the estate of a deceased mandatory income beneficiary whose death causes the interest to end, the beneficiary's share of the undistributed income that is not disposed of under the trust.
     (c) If immediately before the income interest ends, the beneficiary under subdivision (b) has an unqualified power to revoke more than 5 percent of the trust, the undistributed income from the portion of the trust that may be revoked shall be added to principal.
     (d) When a trustee's obligation to pay a fixed annuity or a fixed fraction of the value of the trust's assets ends, the trustee shall prorate the final payment.