Okla. Stat. tit. 60, § 60-175.301: When right to income begins and ends

WHEN RIGHT TO INCOME BEGINS AND ENDS

A. An income beneficiary is entitled to net income from the

date on which the income interest begins. An income interest begins

on the date specified in the terms of the trust or, if no date is

specified, on the date an asset becomes subject to a trust or

successive income interest.

B. An asset becomes subject to a trust:

1. On the date it is transferred to the trust in the case of an

asset that is transferred to a trust during the transferor's life;

2. On the date of a testator's death 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;

or

3. On the date of an individual's death in the case of an asset

that is transferred to a fiduciary by a third party because 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 subsection D of this section, 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.