HARRISBURG - 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.

The Bloomsburg School District last week offered a sign of how bad things may get for the property owners who pay about half of the teachers' pension subsidy. To cope with its growing pension liability, Bloomsburg officials are talking about imposing eight straight years of tax increases.

"Absent stratospheric returns that are hard to imagine and certainly can't be counted on, there's a very big liability that has to be paid," said Bob Gentzel, spokesman for the state government pension system. "Are there things that can be done to sort of ease the slope of the increase? Probably so, but there's nothing to be done that can make the unfunded liability go away."

There is plenty of blame to go around for this potential slow-motion train wreck, not the least being state lawmakers' unwillingness to face up to the consequences of their 2001 vote to increase their own pensions by 50 percent.

It was part of legislation that also increased pensions for about 300,000 teachers and state government workers by 25 percent. And in the following year, lawmakers pushed through a cost-of-living adjustment for retirees.

All those fresh obligations triggered a sudden need for massive taxpayer support, so in 2003 the Legislature and Gov. Ed Rendell then in his first year struck a deal to rejigger the financial structure of the pensions to delay the problem for a decade.

That decade is rapidly coming to a close, and although the pension systems have reaped impressive returns for long stretches of the intervening years, more recently they have both been hammered mercilessly by the drop in the equities markets brought on by the international economic downturn.