The government could save up to $4 billion over 10 years by restructuring the costly and controversial agreements it made in 1988 with investors who took over failed thrifts, the Resolution Trust Corp., the federal agency overseeing the thrift cleanup, said yesterday.

The RTC, unveiling its long-awaited study on whether the cost of the deals could be trimmed, said the government could save the money, in essence, by paying off its obligations to thrift investors early.

Doing that would require a cash outlay of $22 billion in 1991, but that number may not be as big as it sounds since most of that amount -- $16.6 billion -- is money already earmarked for subsidy and interest payments to the thrift investors.

But the report on the RTC's findings, conducted by the Federal Deposit Insurance Corp. and RTC Oversight Board Chairman L. William Seidman, also underscored an array of problems in the '88 deals. The agency study, conducted by outside accountants and lawyers at a cost of $3.5 million, confirmed that enormous financial benefits were bestowed on savvy thrift buyers.

And once again, the overall cost of the '88 deals was revised upward: The cost of the 10-year agreements was put at $69.6 billion, not including tax benefits that have previously been estimated to cost the Treasury $4.5 billion. Since March, the FDIC has placed the cost of the deals at $66.9 billion, plus the cost of the tax breaks.

At the time they were negotiated by the now-defunct Federal Home Loan Bank Board, the cost of the agreements was put at $40 billion.

Yesterday's report also did not figure the overall cost of restructuring if, as the report suggested, early payoffs force 17 of the institutions, holding $51 billion in assets, back into insolvency.

Nevertheless, the new numbers may make restructuring look more feasible to members of Congress anxious to save what billions they can from the ever expanding cost of savings and loan failures.

"This is an obligation of the government, within the four corners of the contracts, to save as much money as possible," said Rep. Charles E. Schumer (D-N.Y.). "This is what every smart businessman would do," he said, noting that the new cash outlay needed in 1991 and the savings involved are close to "a ratio of 1 to 1."

Seidman told the House Banking Committee last week that he expected to have to spend $4 up front for every $1 dollar ultimately saved. That is actually fairly close to the ratio mentioned in yesterday's report.

The report did not attempt to estimate savings that could be made by curtailing some tax breaks to thrift buyers, but Seidman said such savings are potentially substantial.

The 1988 deals have been sharply criticized by members of Congress: A report by the staff of the House Banking Committee concluded that buyers received $78 in assets for every $1 they invested.

"I don't think there's any question that they should save the money," said Rep. Bruce Vento (D-Minn.). "I think the real problem is getting the {Bush} administration to come up here and ask for it."

Seidman said he would hold off making a recommendation on whether to restructure the deals until tomorrow, when he briefs Treasury Secretary Nicholas F. Brady and other members of the RTC Oversight Board.

The chances of getting even more money for the thrift cleanup during the next fiscal year may be slim. As it is, White House and congressional leaders are battling to come up with a plan to reduce the federal deficit by $50 billion next year. If no cuts were made, next year's federal deficit would probably top $250 billion, including $62.3 billion in spending for the RTC.

So far, the budget negotiators haven't even addressed the issue of RTC funding. Treasury officials yesterday said the administration would wait to hear Seidman's recommendations and would study the report. "It is too early to make a judgment," a spokeswoman said.

The report showed that cash-short thrift regulators used creative financing methods to sell debt-ridden institutions to private investors in 1988. Instead of paying investors outright to absorb billions of dollars in losses on bad loans, the government gave buyers promissory notes, which were to be paid off when there was more money in the thrift insurance fund. The government is also paying the buyers a high rate of interest on those notes.

The RTC report said the government could save between $1.1 billion and $1.2 billion by paying off the notes early, but it would need to come up with $10 billion in cash to do so.

The prepayment of a note in one deal alone -- that of American Savings Bank in Stockton, Calif., a thrift acquired by a group led by billionaire Robert M. Bass -- could save the Treasury more than a half a billion dollars. However, doing so would require the government to come up with $7.1 billion in 1991 and 1992.

A spokesman for the Bass group said yesterday that American is willing to restructure its agreement with the government.

Another element of the deals that could be restructured to save money, the RTC report said, are agreements under which the government agreed to pay yearly subsidies to cover the thrifts' cost of keeping foreclosed real estate on the books. The RTC report said the government could buy some of those assets back, and it could end costly subsidy payments on others by paying thrifts the difference between the book value and the actual value of the properties.

Such write-downs could save $535 million in 1991, but they would require $3.8 million in cash up front.

Staff writer Steven Mufson contributed to this report.