(case involves action by government to collect unpaid estate tax from heirs of decedent; estate made I.R.C. §6166 election to pay estate tax in installments, but defaulted after having paid only $5 million of $6.871 million estate tax liability; IRS sought to collect unpaid amount from personal representative of estate and beneficiaries of decedent’s trust who were residual beneficiaries after all expenses and taxes of trust had been paid; major asset of trust was corporate stock; decedent died in 1991, trust assets distributed in 1992, and corporation filed bankruptcy in 2002 with beneficiaries receiving nothing on shares except minor amounts in return for covenant not to compete from the buyer of the corporate assets from the bankruptcy estate; beneficiaries, as recipients of trust distributions not liable as beneficiaries or transferees, but recipients of life insurance liable along with others who were liable as personal representatives; I.R.C. §6234(a)(2) lists categories of persons personally liable for estate tax including “transferee,” “trustee” and “beneficiary”; heirs did not become “distributee” when trust corpus distributed to them because property not received immediately upon date of death of decedent - trust property passes immediately to trustee; term “beneficiary” only refers to recipient of life insurance policy and not to be applied broadly to apply to any recipient of property from estate or trust; IRS not time-barred from collecting against distributes as long as time-period open for collecting against estate – statute of limitations had been extended by I.R.C. §6166 election; under 31 U.S.C. §6166, personal representative that pays any part of estate debt (i.e., distributing assets) before paying governmental claim personally liable to extent of payment for unpaid governmental unpaid claims; personal representative had distributed assets to beneficiaries before estate tax fully paid and become personally liable for any unpaid tax; contribution agreement between personal representative and beneficiaries also made personal representative personally liable if beneficiaries defaulted on obligation to pay unpaid estate tax).