From the overview:
A number of states with defined benefit, or traditional, pension plans have enacted policies that retain the core elements of the plans while sharing the risk of cost increases—as well as potential gains—between public employees and employers. These mechanisms for sharing costs can help reduce volatility and investment uncertainty while preserving the ability to pay promised pension benefits.
For most public sector defined benefit (DB) plans, the cost of providing these benefits fluctuates, depending on investment performance, inflation, salary growth, life spans, and workforce demographics. Cost volatility can strain state or local budgets or lead to underfunded pension plans if policymakers have not provided sufficient contributions.
In response to the budget strains and funding challenges, some states have looked to alternatives to traditional pensions, including defined contribution, cash balance, and hybrid plans. Still, most state and local governments continue to offer DB plans, though many now use cost-sharing mechanisms to reduce budget uncertainty. Employees continue to receive guaranteed lifetime benefits and in some cases see gains, such as higher cost of living adjustments (COLAs), from strong investment returns….
….This map and table highlight strategies used by large state pension plans to share cost increases with members. Looking at the benefits offered to new workers in 102 primary state retirement plans, Pew’s public sector retirement systems project identified 28 plans in 16 states that use formal cost-sharing mechanisms to manage risk….