This document contains final regulations that provide guidance under the anti-cutback rules of section 411(d)(6) of the Internal Revenue Code, which generally prohibit plan amendments eliminating or reducing accrued benefits, early retirement benefits, retirement-type subsidies, and optional forms of benefit under qualified retirement plans. These regulations provide an additional limited exception to the anti-cutback rules to permit a plan sponsor that is a debtor in a bankruptcy proceeding to amend its single-employer defined benefit plan to eliminate a single-sum distribution option (or other optional form of benefit providing for accelerated payments) under the plan if certain specified conditions are satisfied. These regulations affect administrators, employers, participants, and beneficiaries of such a plan.