The banking "reform" bill that Congress passed as it went home for Easter was advertised as a boon to borrowers. But it turns out that lenders did pretty well, too -- especially big banks.

One part of the complicated bill relaxes so-called reserve requirements that say how much of their deposits banks must keep in reserve and how much they can lend.

This means that the nation's larger banks, which are most affected by the requirements, will be able to lend out -- and earn interest on -- about $18 billion over the next four years that they otherwise would have had to hold back.

Bank of America, the largest of the banks, will have about $1.2 billion of its funds freed in this way. Citibank and Chase Manhattan each will gain an extra $450 million to dabble with.

The diminished requirements were part of a compromise intended to increase the Federal Reserve Board's control over the banking industry.

Under the compromise, all lending institutions will be subject to the Fed's reserve requirements, but those requirements will be less onerous for some than in the past. The Fed, which sought the new provisions, thinks it will end up with more power over the money supply.

The reserve requirement provisions are typical of the trade-offs that are evident throughout the heavily lobbied banking bill.

For years the U.S. lending industry has been Balkanized by law into separate and largely competitive compartments, with the banks on their special turf, savings and loan associations on theirs, and so on.

The banking bill removes many of these former boundaries, leaving most financial institutions on about the same footing. Every sector of the industry loses some previously held advantages. But as with big banks and the reserve requirements, every sector also acquires some new advantages.

The reform measure was so complex that, at one point on the House floor, a Banking Committee aide was carrying around a voluminous computer print-out to show any member how the bill would affect his hometown banker.

As it turned out, almost every group involved appears to have gotten what it wanted.

The Fed got what it wanted most, the reserve.

The savings and loan institutions got expanded powers that will make them much like banks. In return, they grudingly -- and slowly over the next six years -- will give up the ceiling on the interest rates they pay small savers.

Everybody got to offer interest on checking accounts and the right to override state limits on interest rates on many loans.

The consumer eventually will get a higher rate on passbook savings and a chance to shop around for interest on checking accounts.

There were a few voices of criticism. Ellen Broadman of Consumers Union called the bill a "creditors' relief act." Rep. Frank Annunzio (D-Ill.), chairman of the House Banking consumer subcommittee, was so angry at the final product that he refusded to sign the House-Senate conference report.

But all sides agree that the Depository Institutions Deregulation and Monetary Control Act of 1980 is a momentous step for the people who buy and sell money: the nation's bankers and their customers.

The new law is a conglomeration of several major bills that had been kicking around for years. Until now, infighting among the various interest groups had blocked such sweeping change of the financial system.

Lobbyists say they are still pinching themselves in disbelief that the deal was cut.

"I'm still amazed that the different constituencies did come together, that the linkages did hold," said Ed Smith, spokesman for the American Bankers Association.

A review of the process, and interviews with many of the participants, show that a combination of pressures -- inflation, a court-ordered deadline and perhaps the pschology of facing the complicated package yet again -- combined to push through a massive bill that few other than the financial lobbyists understand fully.

In the end much of the bill was written in conference. Seven of its nine titles, in fact, were never marked up by the House. There was only the final up-or-down vote.

"It's an incredible way to legislate," said Jonathan Brown of Ralph Nader's Public Interest Research Group.

"That bill is a Christmas tree for the big banks. People didn't know what they were voting on," one critic said. Another observed: "I think the president thought he was signing Amy's report card."

Nonsense, say the bankers and the chairmen of the Banking committees, Sen. William Proxmire and Rep. Henry Reuss. The two, both Wisconsin Democrats, were the chief sponsors of the bill.

Participants agree that spiraling inflation spurred their deliberations and made competing interests more open to compromise. Federal Reserve Board Chairman Paul Volker pushed hard for the universal reserve requirement. The savings and loan industry realized that Regulation Q, the rule that limits interest paid to passbook savers, no longer was helping to make money available for housing loans.

Consumer lobbyist Brown said it would have been unthinkable even a few years ago for the homebuilders and savings and loans to give up on Regulation Q, even gradually, because it set bank passbook interest rates a quarter of a point lower than those of thrift institutions.

Some critics of the new law charge that it throws in the towel on fighting inflation, since it raises the ceilings on interest rates for both loans and savings. Financial lobbyists counter that it recognizes the reality of today's volatile economy.

"We do have to make accommodations for the financial system to work in this inflationary period," said a White House official who had been involved in the process.

Here's a closer look at the major provisions of the new law and where they came from:

Reserve Requirements: Reuss was the main backer of this provision in Congress and he got plenty of help from Volcker and Rep. J. William Stanton (Ohio), the committee's ranking minority member.

The Fed said it needed the universal requirement to stop the exodus of its member banks, who quit the Fed system rather than continue to keep some deposits in non-interest-bearing reserves.

For the first time, the Fed also will charge for services it offers its members. For years it has subsidized the nation's largest banks by doing their check clearing.

Regulation Q: Proxmire considered the lifting of the interest rate paid small savers as the keystone of the bill, and refused to go to conference with the House last fall until they came up with a way to deal with Regulation Q, too.

The savings and loan lobby finally agreed to lift the ceiling, but argued it would have to be gradual because much of its loan portfolio is tied up in old, low fixed-rate home mortgages.

Interest on Checking accounts: Both houses had bills to legalize such accounts that exist now in New England, and to expand such authority nationwide.

Lobbyists for all the financial institutions said they envision a wild competive scramble at year's end to lure customers to open the new interest-bearing accounts.

Skeptics note that the experience in New England shows such accounts usually require a very high minimum balance -- sometimes $3,000 -- or else service charges add up to more than the interest paid. Proponents of the plan say that consumers will have to have the sense to shop around and calculate whether the new accounts will help them.

Expanded Powers for Thrifts: Savings and loans, credit unions, and mutual savings banks will get a flock of new powers that eventually will make them almost the same as banks. Savings and loans, which have been facing a profits squeeze, will be able to make some consumer loans, and offer credit cards and trust services.

Credit unions will get to charge 15 percent for loans, up from the current 12 percent limit.

And, at the urging of the savings and loans, insurance on accounts will jump from $40,000 to $100,000. Already, full-page newspaper ads have trumpeted this "good news," through consumer groups scoff at this purported boon to the saver.

In reality, participants said, the big California savings and loans pushed this provision -- which didn't appear in either bill -- in conference as a way to hang on to holders of "jumbo" certificates of deposit.

Override of State Usary Laws: In one of the great political buck-passing jobs in recent time, members of several state legislatures privately urged Congress to override their unrealistically low usury laws. This way they can blame Washington for boosting interest rates on loans.

States can override the override only if they pass a measure that refers "explicitly" to the new law.

Truth-in-Lending: It is called "simplification" in the bill. It is called murder by the consumer groups and Annunzio.

Consumer Union's Broadman said that a little-noted provision of the change forgives the financial institutions an estimated $400 million in overcharges that federal regulators have discovered in past examinations.

One new banking law amendment is being referred to in some circles as the "big banks' REIT bailout."

This refers to the provision that allows banks with real estate investment trusts to hold property for an additional five years and improve it before selling it to recover its investment.

Drafters acknowledge it was designed to help banks who were caught holding millions of dollars in bad real estate loans when the real estate trusts that many of them spawned crashed in the mid-'70s recession.

Some participants in drafting the bill didn't even know that provision was there. "We'll be finding little goodies like that for months to come," one said with a chuckle.