PROVIDENCE –– Governor Carcieri has cut the state’s work force to its lowest level in recent memory, leaning heavily on a change in retirement benefits that pushed hundreds of workers into retirement earlier than they had planned.

But the exodus has put an unexpected strain on Rhode Island’s public retirement system.

There are now fewer active employees paying into the pension system and more people collecting retirement payments than had been predicted.

The result is a projected hole of $20.4 million that Rhode Island taxpayers will make up in the coming year. That price tag may be offset by savings this year, but the jump in those collecting pensions also adds $33 million to the retirement system’s already massive unfunded liability, according to a report by the state’s actuary, Texas-based Gabriel Roeder Smith & Company, that was made public yesterday.

Officials interviewed yesterday dismissed the new costs as necessary and relatively insignificant given the overall savings from the retirement of 1,521 state employees between May 1 and Sept. 30.

The governor’s office says it could save taxpayers $107.6 million if none of the vacancies is filled (not including $18.8 million distributed for things like unused sick and vacation time).

“This is something that is a good story for us in the medium and long term,” said General Treasurer Frank T. Caprio, who heads the state pension system. “The State of Rhode Island reduced its employee cost by 18 percent. Whether you are a private company, a family-owned company or any other organization, to reduce your payroll costs by 18 percent in one year is a major accomplishment and I believe a victory for the taxpayers.”

The governor’s personnel office reports that the state currently employs the equivalent of 13,302 full-time workers.

That’s the lowest level that state personnel administrator Anthony Bucci can remember. The House Fiscal Office has tracked employee data since 1994 and could not find a lower employment total.

Even the Rhode Island Public Expenditure Council could not determine when the state had fewer than 13,302 full-time workers. The business-backed organization tracked employment levels back to 1990, when nearly 17,500 people were on Rhode Island’s payroll.

“Even with the retirement payouts and the added costs to the pension, we are still seeing a significant savings in personnel,” the governor’s spokeswoman, Amy Kempe, said.

But the state Retirement Board was forced to address the unexpected pension costs yesterday.

Following a recommendation by the actuary, the board voted unanimously to close the projected $20.4-million gap by changing the formula used to determine the state’s annual contribution to the pension system. Its contribution rate for the coming year jumped from 20.69 percent to 25.03 percent.

State employees contribute a portion of their salary –– currently 8.75 percent as set by law –– to their pensions. But that’s not enough to cover the costs. Yesterday’s vote means that taxpayers will contribute $147.8 million to the system next year.

The contribution would have been $20.4 million short had the board not changed the rate, according to Frank J. Karpinski, executive director of the retirement system.

“You got more people going out the door than what we expected. You took a little bit of a bath, so to speak,” he said, noting that over the long term, taxpayers won’t pay more than they would have. It’s just that a new burden was shifted to next year, he said.

The actuarial report released yesterday also notes that the pension fund “has had significant losses” in recent months. While it did not detail the losses, the treasurer’s office later reported the fund had slipped to $6.2 billion as of Oct. 31; it was worth $8.3 billion on Jan. 1.

The loss –– about 25 percent –– is better than the national “policy benchmark” of 27 percent, according to Caprio.

“Even though markets have retreated over the last year, Rhode Island has not had any forced liquidations,” he said. “We have the necessary cash on hand to meet our obligations. Many other funds cannot say that.”

speoples@projo.com