The Carter administration may be headed for a showdown with Congress over a House subpoena for the records of wiretaps instituted without court orders over the past 20 years at the government's behest.

The chief congressional protagonist in the dispute, Rep. John E. Moss (D-Calif.) said the underlying issue was an unprecedented claim of executive privilege - first asserted by president Ford and thus far maintained by the Carter administration - for documents belonging to a private corporation, in this case the American Telephone & Telegraph Co.

Moss said negotiations with Attorney General Griffin B. Bell were undertaken last month but had proved fruitless. The Justice Department yesterday informtd House lawyers it was circulating a possible compromise calling for in camera inspection of the records by a U.S. District Court judge, but Moss denounced the offer as more restrictive than one proposed under Ford.

"It's an absolute outrage that they should try to erect this kind of a barrier," Moss said last night of the tentative administration offer! "It's the kind of a proposal you might make to a subordinate. I don't find it consistent with maintaining the independence of the Congress."

U.S. District Court Judge Oliver Gasch is scheduled to receive a progress report on the dispute, which has been simmering in the dourts since last summer, at 4:30 p.m. today.

Moss predicted that the impasse would result in Gasch's sending the case back upstairs to the U.S. Court of Appeals, and then to the Supreme Court if necessary.

"There are few issues more fundamental to the rights of Congress than the right to inquire," Moss said yesterday at a House Administration subcommittee hearing where he asked for $55,000 in special legal fees to carry the case as far as the Supreme Court.

At issue are AT&T's records containing the telephone numbers tapped without court order at the request of the FBI, which served as the intermediary for all government agencies. According to aides to Moss, official inventories indicate there were approximately 700 such taps reflected in the mammoth utility's records, dating back as far as 1956.

The confrontation began to take shape last summer when Moss' Commerce Oversight and Investigations Subcommittee subpoenaed the documents to determine the degree of AT&T compliance with the 1934 Communications Act.

"The Communications Act ensures, or is supposed to ensure, the privacy of communications in this country," Moss said. The Supreme Court held in 1969 that so-called 'domestic security' wiretaps could not be initiafed without a court order.

Negotiations with the Ford White House and the Justice Department, which were anxious to keep secret the names of those tapped, at one point produced a written agreement whereby the Moss subcommittee would have been allowed to look at expurgated FBI backup memoranda justifying each tap and to inspect a fair sample of the complete records, including some names and numbers.

Moss was prepared to go along, but then, he said, "everything went to pieces because of the opposition of the Central Intelligence Agency." In a letter to the House Commerce Committee last July 22, Ford took the position that AT&T, in receiving, acting upon and maintaining the disputed records, was simply "an agent of the United States" whom he was instructing "to respectfully decline to comply with the committee's subpoena."

When AT&T balked, saying it was no government agency, the Justice Department went to court and obtained an order from Gasch blocking the phone company from honoring the subpoena. After an interim consideration by the U.S. Court of Appeals, the case was sent back to Gasch to see if he could preside over an acceptable compromise, but Moss said this had not been possible.

He said the dispute was particularly absurd because testimony by AT&T officials has established that some 50 employees of the phone company and its subsidiaries, many without security clearances, have had routine access over the years to the records being denied to the Congress.

Deputy White House press secretary Rex Granum had no immediate comment. Moss said he had hoped for more openness from the Carte administration but was not really surprised at its efforts to maintain the secrecy of the records.