For this calculation, actuaries assume a rate of return on all the money invested. The assumed rate of return, or “discount rate”, makes a big difference in how big current liabilities might be. For example, if you invested enough now to pay back a $100 debt in 10 years and you expected a rate of return of 5 percent each year, you would need to invest $61.39. But, if you expected an 8 percent return each year, you would only need to invest $46.32 today.
Arizona’s government pension funds use a discount rate of either 8 or 8.25 percent, considerably higher than the 5 percent they have actually earned over the last decade. Consequently, while Arizona’s unfunded pension liabilities are officially $16 billion, a huge sum, the unfunded liabilities using the actual rate of return of 5 percent are more like $37 billion. That’s $5,800 for every man, woman, and child in the state.