Md. Code, Estates and Trusts § 9–206

If a holder disclaims a power of appointment or other power not held in a fiduciary capacity, the following rules apply:

(1) If the holder has not exercised the power, the disclaimer takes effect as of the time the instrument creating the power becomes irrevocable;

(2) If the holder has exercised the power and the disclaimer is of a power other than a presently exercisable general power of appointment, the disclaimer takes effect immediately after the last exercise of the power; and

(3) The instrument creating the power is construed as if the power expired when the disclaimer became effective.