(a) General. -- The amount of estate tax due under this article shall be assessed on or before whichever of the following dates occurs last:
(1) The period specified in section fifteen, article ten of this chapter, during which an assessment may generally be issued;
(2) Within a period expiring ninety days after the last day on which the assessment of a deficiency in federal estate tax may lawfully be made under applicable provisions of the Internal Revenue Code; or
(3) Within ninety days after receipt of notice from a personal representative that the federal estate tax liability of an estate has been changed.
(b) Exceptions. -- In the case of a false or fraudulent return, or failure to file a return on or before the last day prescribed for filing, or failure of the personal representative to give the tax commissioner notice of a change in the federal estate tax liability of an estate, the tax may be assessed at any time.