The goal of this paper is to review and comment on certain aspects of the Pension Insurance Modeling System (PIMS) and certain actuarial assumptions used by PIMS. The apparent stability of the deficit and funding ratio of the PBGC are partially dependent on a continued stream of premium payments from plan sponsors. However, derisking and other trends among retirement plans may change the pattern of premium income. Deterministic projections that supplement the stochastic simulations may enhance the understanding of the current deficit and the projected net claims over the next ten years.