Pennsylvania's day of reckoning over its multibillion-dollar pension promises to government employees and teachers has been pushed back for the better part of the past decade.

But long-expected increases in costs are scheduled to kick in three years from now, and meeting those retirement obligations could cripple state government and school boards.

Depending on what happens in the stock market, taxpayers could soon find themselves stuck paying more than $5 billion in additional annual payments.

The figure is a moving target. But in a March presentation to a state House panel, the state's two large public-sector pension plans estimated that the $821 million a year they currently get in "employer contributions" - the vast majority of it from taxpayers - will need to grow to $5.7 billion a year by 2012.

Even more frightening is that those numbers involve assumptions that could be overly optimistic. For example, the state government pension system's numbers assume it will earn 8.5 percent this year, but its 2009 investments are currently about 6 percent in the red.