In In re Estate of Leitham, 726 A.2d 1116 (Pa. Cmwlth. 1999), the Department of Revenue filed a notice assessing additional inheritance tax and also penalties and interest more than eight years after an estate filed its inheritance tax return, based on failure to include the decedent's retirement plan in her taxable estate. The estate did report the proceeds on its federal estate tax return, a copy of which was filed with the state return. The trial court affirmed the imposition of the tax, although it ordered that the estate and its beneficiaries were not liable for interest and penalties because the delay in filing the notice was attributable solely to the Department. The Court explained in In re Estate of Leitham that in the years since the Department failed to timely file an appraisement, determination or assessment, the estate had been closed and assets distributed. Defending against or complying with the notice at that time presented an unfair hardship. Referring to the historical reluctance of the courts to apply estoppel to the government, the Court noted that the reasons offered were strikingly similar to the reasons supporting the doctrine of sovereign immunity and that both had been modified in recent years, so that application of estoppel should not be denied merely because it was asserted against the government, as indicated in Department of Public Welfare v. UEC, Inc., 483 Pa. 503, 397 A.2d 779 (1979). The Court addressed Western Maryland Ry. Co. and stated that modern advances in case law left intact the principle enunciated there that failure to collect the tax in the past is no bar to present collection. Because the estate did not seek insulation from future tax liability, Western Maryland Ry. Co. was inapposite. The Court reversed the trial court.