Taxpayers who unknowingly contributed a substantial chunk to President Reagan's last inauguration may be off the hook this time, at least for the cost of exclusive events they couldn't attend.

Under new direction from Congress, the Pentagon intends to seek reimbursement for its services and supplies for private events at President-elect Bush's inauguration. The private Presidential Inaugural Committee intends to pay that tab.In 1985, seven federal agencies spent nearly $16 million on the Reagan festivities - with the Defense Department accounting for $10 million.

Three weeks before the inaugural period begins, the committee has yet to tell the Pentagon how many military men and women it will need for its galas, celebrations and other activities.

But Capt. Gail Hayes of the Armed Forces Inaugural Committee said her committee does not anticipate a decline in the number of people it will be asked to detail to inaugural duties.

"Our best estimate is that DOD participation will be 8,500 people," she said - the same as in 1985.

While the participation level could be equally high, the bill to taxpayers should not.

Tucked deep in the defense authorization act for fiscal 1989 is a paragraph saying the defense secretary should seek reimbursement for troops used at private inaugural events, and only volunteers should be used at such events. It was sought by outgoing Sen. William Proxmire, D-Wis., well-known for his efforts to curb what he considers wasteful spending.

Proxmire was moved by a General Accounting Office report last year that detailed federal spending on the 1985 inauguration and noted that soldiers had been used - sometimes unwillingly - as chauffeurs, photographers and escorts.

Ron Tammen, Proxmire's administrative assistant, said the new policy is meant to relieve military people of chores such as driving VIP spouses to beauty parlors and to restrict federal subsidies of balls and other events he described as "virtual political payoffs."

"We specifically meant to prevent the use of the military at balls and galas, which are exclusively to entertain the VIPS - (Bush) supporters and Republicans," Tammen said.

Despite some confusion about the provision at the Pentagon and the inaugural committee, both say they will heed the guidelines.

"The Department of Defense does intend to seek reimbursement where appropriate for support rendered," said Hayes, defining "where appropriate" as meaning private events.

"We'll make sure that we comply," said Stephen Studdert, executive director of the Presidential Inaugural Committee.

Studdert said it had not been determined which inaugural events would be considered private as opposed to public. But general counsel Jan Baran said an event is considered public if 50 percent of the tickets are available to the public, and by that standard, about one-third of two dozen activities are public.

Among the open events are a parade, a pageant, a children's festival, an "American Tribute to Democracy" and a thanksgiving service at Washington Cathedral. There are more than a dozen private events including nine balls, a worship service, a dinner, a gala, a vice presidential reception, a salute to the first lady and a celebration for young Americans.

PIC and Pentagon officials were unclear about how much the Pentagon can expect to be repaid or what impact the new policy will have on the inaugural committee's $20 to $25 million budget.

"It's hard to measure," said Studdert. "It may not add on to the overall cost. We may save on other categories by increasing volunteer use. That's our hope."