RSA 563-B:9: Disclaimer by Appointee, Object, or Taker in Default of Exercise of Power of Appointment.

(a) 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.

(b) A disclaimer of an interest in property by an object or taker in default of an exercise of a power of appointment takes effect as of the time the instrument creating the power becomes irrevocable.