The automated teller machine, which was going to bring space-age efficiency to banking, has turned out to be so expensive to own and operate that banks are beginning to charge customers for transactions at the banks' own ATMs.

Last April, Maryland National Bank began charging 35 cents for each ATM transaction, and First Virginia Bank has informed its customers that they will have to pay a quarter each time they withdraw cash from one of the bank's machines, beginning Thursday.

The imposition of fees for the use of ATMs is widely expected to increase, though industry experts differ on just how much or how fast. Banks have long charged customers for the use of machines not located on the banks' premises, but fees for the banks' own units are a new development here.

While other local bankers contacted said they had no plans to begin charging, several said they understood that other institutions were considering doing so.

In other markets, such fees are somewhat more common. Industry groups estimate that about 20 percent of the nation's banks impose them; a 1986 survey by the American Bankers Association showed that only 12.7 percent of small banks charge them, compared with 31 percent of large banks.

Spencer Nilson, publisher of the Nilson Report, a credit card newsletter based in Santa Monica, Calif., said, "Eventually everyone will charge." He predicted that fees will average 75 cents soon and ultimately will reach $1.

Banks that have imposed the fees say they did so to avoid losing money on ATMs. "I think there is general agreement that ATMs cost a lot more than anticipated," said Larry Watson, director of marketing for First Virginia. He said that the promise of great savings has turned out to be "a false premise" that ATM makers used to sell the machines to banks.

"It was one of the ways they positioned these things, that they were going to reduce costs and everyone was going to be using ATMs," Watson said, adding, "A significant number of people are using ATMs, but not nearly as many as anticipated."

The charges are another step in the banking industry's effort to devise a fee structure that allows day-to-day operations to cover their costs without a subsidy from lending operations.

Maryland National began charging for use of its own ATMs last April after analyzing its experience with ATMs and finding that the machines were costing the bank more than it expected.

"We now know what the true cost of operating our network is and have just realized that those costs are higher than we thought," said Jill Springer, a spokeswoman for MNC Financial, Maryland National's parent company in Baltimore.

She said the bank's 135 ATMs cost about $7.8 million a year to operate and "the fees are designed to recoup some of that." She said, "We don't intend to have the customer pay the entire cost of operating the system."

She also noted that while the fee applies to any ATM transaction, only 30 to 40 percent of the bank's customers actually have to pay it. Those who maintain minimum balances of $500 a month or who have certain other types of accounts are exempt.

Springer also said the bank has not met with much customer resistance to the fees, nor has there been a significant drop in ATM card use. "I think that it's a convenience that most customers are willing to pay for," she said.

This matches the findings of the ABA survey, which found that banks with fees "have not run into resistance from consumers," primarily because consumers perceive the cards as providing a valuable service that they are willing to pay for.

Other bankers and banking experts echoed that sentiment.

First Virginia's Watson said, "We think it's a reasonable fee" that will cover the bank's costs. First Virginia's fee covers only cash withdrawals, but it applies to all accounts, he said. He noted that ATMs give customers access to their money "24 hours a day, seven days a week," a service they wouldn't have without the machines.

Ed Alwood of the ABA added, "It's not the same service it was five years ago." ATM cards allow customers to get money not only after hours but in distant places. "I can get cash 24 hours a day in New York," he said.

Industry spokesmen also said two major deregulations have thrown off initial ATM cost calculations. First, banking deregulation has compelled banks to pay interest on a wide variety of deposits that formerly were interest-free. That has increased costs, forcing banks to examine each of their individual services for profitability.

Second, telephone deregulation has resulted in sharply higher line charges, they said, increasing the cost of hooking ATMs to central computers.

Nilson said ATMs cost banks less per transaction than do tellers, but in the beginning "nobody ever thought about maintaining the machine... . Sure it's cheaper per transaction, but the upkeep is very expensive."

He said that purchasing and installing an ATM can cost $20,000 to $35,000. When all the costs, such as communications hookups, data processing, armored car service and liability insurance for "when someone gets robbed after taking money out and sues you" are factored in, an ATM can cost $200,000 a year.

Some banks are moving aggressively to control ATM costs rather than charge fees. Bruce Gouldey, vice president of Mellon Bank in Pittsburgh, said his company does a profit-and-loss analysis on each of its ATMs every month. "We have done a number of things to get costs down to a manageable level," he said. These have ranged from reconfiguring telephone hookups to eliminating deposits at "off premises" terminals.

Not taking deposits "can dramatically reduce the cost of operating a machine," he said. "If you take deposits at a remote ATM you must go there every single day to balance the machine, whereas it can be once a week or so if you don't take deposits."

Asked about the performance of Mellon's machines compared with original estimates, Gouldey said the question was meaningless: "Nobody knew what ATMs were going to cost."

Staff researcher Bruce Walker contributed to this article.