PBGC, the trustee of a pension plan administered by the CF&I debtors prior to filing their bankruptcy petitions, sought a determination of the priority of its claims for unpaid minimum funding contributions ("unpaid funding") and unfunded prepetition and postpetition benefit liabilities ("unfunded liability") in the bankruptcy court. The bankruptcy court ruled that: (1) unpaid funding claims were not entitled either to administrative expense priority under 11 U.S.C. § 503(b)(1)(B), or tax priority under 11 U.S.C. § 507(a)(7); (2) only a small portion of the unfunded liability claims were entitled to tax priority; and (3) the CF&I debtors were jointly and severally liable for PBGC's claims under the Employee Retirement Income Security Act ("ERISA"). Both sides appealed. The district court agreed with the bankruptcy court that the CF&I debtors' liability for unpaid funding arose prepetition and, therefore, the bankruptcy automatic stay precluded imposition of either an ERISA lien or an Internal Revenue Code lien for those claims. Since tax priority is given only to liens, not claims that never become liens, the bankruptcy court correctly ruled that the unpaid funding claims were not entitled to tax priority status. Additionally, because the unpaid funding claims were not entitled to tax priority, they were likewise not entitled to postpetition interest. The district court also agreed with the bankruptcy court that, under In re Amarex, Inc., 853 F.2d 1526 (10th Cir. 1988), the unpaid funding claims, all of which arose prepetition, did not qualify as administrative expenses. PBGC asserted tax priority with respect to a very small portion of its total unfunded liability claims, based on a statutory lien that attaches to an employer's property upon termination of a pension plan, but the district court agreed with the bankruptcy court's conclusion that, since the plan was terminated postpetition, that lien never attached. Finally, the district court held that the bankruptcy court had erred by deferring to PBGC's determination of the discount rate to be applied to its unfunded liability claims, and remanded for an independent discount rate determination. The district court then rejected the CF&I debtors' claim of improper valuation of the unpaid funding claims, as moot, and held that ERISA's joint and several liability provision was not overridden by the bankruptcy principle of equal distribution among creditors.