(decedent died in late 2007 and estate tax return filed in early 2009 with "estimated" denoted at top of form; return reported gross estate of $13,810,000, tentative deductions of $550,000 and tentative tax listed as "unknown"; return indicated that litigation was pending between decedent's estate and decedent's surviving spouse that had been purportedly disinherited under decedent's will which impacted the amount, if any, of the marital deduction and, consequently, the estate tax due; IRS assessed over $5 million of estate tax against estate and estate objected noting the pending litigation barred computation of estate tax due; litigation settled in mid-2009 and estate filed two amended returns both reporting no tax due; IRS determined that over $2 million in estate tax due; estate sought IRS issuance of notice of deficiency so that alleged deficiency could be litigated; IRS issued notice of deficiency in late 2011 and estate filed Tax Court petition in early 2012 and IRS moved to dismiss for lack of jurisdiction on the basis that a prior assessment of estate tax eliminates any "deficiency" over which the court has jurisdiction; IRS also claimed its notice of deficiency issued as protective measure if prior assessment found invalid; estate moved for summary judgment on basis that statute of limitations barred issuance of revised notice of deficiency ; court rejected IRS' motion to dismiss, finding that prior assessment was invalid, but determined that notice of deficiency was valid because it had been timely issued and complied with I.R.C. Sec. 6212 and did not violate I.R.C. Sec. 7522; court has jurisdiction and case to proceed to trial).