This chapter shall apply to the estates of all decedents dying hereafter and to the estates of those who died subsequent to February twenty-sixth, one thousand nine hundred and twenty-six, which are still in process of settlement and subject to the jurisdiction of the courts of probate of this state, but shall not apply where the inheritance, succession or legacy tax due the state has been fully paid and the inheritance tax proceeding considered closed by the state tax commissioner, or where the estate tax due the United States has been fully paid and the time within which to claim the benefits of the credit provision of the federal revenue act of one thousand nine hundred and twenty-six, or any modifications thereof has expired prior to June twenty-second, one thousand nine hundred and thirty-four.