The arithmetic on the chained CPI is straightforward. It reduces benefits by an amount that increases 0.3 percentage points each year a person is retired. This means that after 10 years the reduction in the annual benefit would be 3.0 percent, after 20 years the reduction would be 6.0 percent, and after 30 years the reduction would be 9 percent. If we assume that a typical beneficiary lives long enough to collect benefits for 20 years, their hit from the chained CPI would on average be 3.0 percent over this period.