Previous year numbers are usually finalized in the spring, and contribution rates approved in June. Bookkeeping is delayed this year because of several changes made to the retirement system by the union law and the biennial budget.

It's complicated because so many fluid factors — salary levels, retirement rates and investment returns — influence the finances of the state pension fund. Overall, employer and employee contributions to the fund totaled $1.5 billion in 2010, the latest year for which exact data is available. Under union contracts, nearly all of it was paid by employers.

Act 10 was Gov. Scott Walker's signature legislation, designed to rein in government costs. Spokeswoman Julie Lund said Walker wants a strong pension fund, but she didn't directly address Stella's criticism.

About 75 percent of the fund is generated by investment income, with the remainder contributed by employers and employees.

The 2013 cost to be split by government employers and employees may reach from $1.6 billion to $1.7 billion according to State Journal analysis of the projections released Thursday.