No they planned for the spike, but they were a percent off or so. it happens, guess what they did not plan for a decrease in life expectancy in 2020 but it happened.
You can go back and look at every single report by the SSA administration, they have it on line.
https://www.ssa.gov/OACT/TR/historical/1994TR.pdf
in 1994 they said 2020 would be 75/81.2. Their high cost projections were 76.7/82.9. Current rates: Male: 76.1 years - Female: 81.1 years. Not bad for a 25+ year prediction huh?
Where they fell short
-income projections relative to cost. We all know wages have been stagnant for decades for a large portion of the working population. The folks who saw the most increases have incomes that are not subject to the tax.
- Interest rates. Long term projections set them at 6.3%
- Labor force increase .5-2% a year. Yah they got this really really wrong. got it right on the high cost projection though.
- Wage increase of 5% a year from 2010-2070.
- Though they over estimated unemployment.
They keep them on file for you to read.
They also said in the 1990s the halting of any adjustments to taxes, retirement age and income limits would cause insolvency.
And no its not a Ponzi