Many banks are rushing into electronic fund transfer systems without a clear idea of what either the true costs or benefits are, according to a new study released today by Peat, Marwick, Mitchell & Co.

"Judging from our interviews during this study, financial institution officials pay little attention to determining the cost of developing their EFT system," the study said.

"In most cases, even when we requested only an estimate, either none was available or a rough calculation of costs was all that could be quoted," it continued.

Benefits were "even harder" to identify because "electronic bank ing cannot be insulated from other, extraneous influences," it said.

The 200-page Peat, Marwick report was sponsored in part by the National COmmission of Electronic Fund Transfers and presents a descriptive roundup of nearly 300 electronic banking projects in 28 states and the District of Columbia and also summarizes developments in all 50 states and the District.

Concerning the District, the report says that commercial bank EFT activity there has been suppressed due to the Supreme Court's recent refusal to review a lower court ruling that said remote terminals for many transfer transactions would have to be considered as branches.

"The decision to consider off-premises EFT facilities branches is particularly frustrating to District bankers who, hoping to gain access to both the lucrative suburban Maryland and Virginia markets, had envisioned remote service units as the means to escape the confines of their market, limited by law to the District," the study noted.

The District's credit unions "have led in local EFT activity," according to the report, but "it is expected that D.C. commercial banks will soon begin to expand their EFT development."

The study points out that six District financial institutions - American Security & Trust Co., National Bank of Washington, Riggs National Bank, columbia Federal Savings and Loan Association, Perpetual Federal Savings and Loan Association and National Permanent Savings and Loan Association - have gotten together to jointly sponsor a study on the feasibility and cost-effectiveness of EFT implementation.

The report is inconclusive about consumer acceptance of electronic banking - the key to its ultimate success or failure - but says that aggressive marketing and advertising campaigns have managed to "speed the process" in some cities.