However, the reason assumptions remain high is simple. If these rates were lowered 1–2 percentage points, the required pension contributions from salaries, or via taxation, would increase dramatically. For each point reduction in the assumed rate of return would require roughly a 10% increase in contributions.
For example, if a pension program reduced its investment return rate assumption from 8% to 7%, a person contributing $100 per month to their pension would be required to contribute $110. Since, for many plan participants, particularly unionized workers, increases in contributions are a hard thing to obtain. Therefore, pension managers are pushed to sustain better-than-market return assumptions which requires them to take on more risk.