Or. Rev. Stat. § 105.639 – Disclaimer by appointee, object or taker in default of exercise of power of appointment

(1) A disclaimer of an interest in property by an appointee of a power of appointment takes effect as of the time the instrument by which the holder exercises the power becomes irrevocable.
(2) A disclaimer of an interest in property by a person who is an object of an exercise of a power of appointment, or by a person who is a taker in default of an exercise of a power of appointment, takes effect as of the time the instrument creating the power becomes irrevocable.

[2001 c.245 §10]