The D.C. educational tax credit initiative failed to win approval in any of the city's 137 voting precincts Tuesday and lost in one by 38 to 1, according to uncertified returns released yesterday by the Board of Elections and Ethics.

Despite an estimated $135,000 campaign by the National Taxpayers Union, including a last-minute television advertising offensive, the initiative was overwhelmingly rejected by every segment of the city's electorate -- from the wealthy neighborhoods of upper Northwest to the poorest areas of Anacostia.

The unofficial citywide totals were 73,829 against the initiative to 8,904 in favor -- an 8-to-1 landslide margin that national education and labor leaders said should severely damage efforts to pass similar measures on a national level or in other states.

The votes for the initiative were less than one-third of the 27,415 signatures that proponents had collected on petitions to put the measure on the ballot.

The sponsors had initially hoped to pick up support among Catholic school parents and from Ward 3, the largely white and affluent part of the city west of Rock Creek Park.

Many parents there send their children to private schools and would be expected to directly benefit from the proposal for a $1,200 a pupil tax credit for tuition and other educational expenses.

Although the initiative fared best in Ward 3, it nevertheless lost there by a crushing vote of 13,401 to 3,187 -- a 4-to-1 margin. In Ward 4, which is home for many middle-income blacks with children in private schools, the proposal lost 14,020 to 1,154 -- a 12-to-1 margin.

Proponents also appealed to low- and middle-income blacks by stressing in their campaign advertisments that the credit would allow poorer children to escape from bad public schools -- a claim that initiative foes said was a "hoax."

But overall, the proposal fared worst in Wards 5, 7 and 8 -- predominantly black low- and-middle-income areas that include the highest concentration of students in public schools -- getting just 7 percent of their votes.

The proposal did best in two of the city's wealthiest neighborhoods -- Precinct 9 in Spring Valley and Precinct 6 in Georgetown. But even there it received less than 29 percent of the vote.

In Precinct 99, located around Woodson Junior High School, Minnesota Avenue and Foote Street NE, the initiative lost by a vote of 267 to 7 -- a 38-to-1 margin that was the largest in the city.

National education and labor groups, which have vigorously opposed tax credits and other state and federal proposals to aid private schools and were the principal source of finances for the opposition here, said the crushing 8-to-1 defeat had national significance.

"This vote should send a clear message to Sen. Daniel Moynihan D-N.Y. and others in the Congress who have been trying to get federal tax credit legislation passed," said Albert Shanker, president of the American Federation of Teachers, at victory party of tax credit foes Tuesday night.

"This is the first chance the people have had to say whether they wanted it or not, and they turned it down overwhelmingly," Shanker said.

Charles Pike, a Libertarian Party activist who had managed the campaign in favor of the initiative for the D.C. Committee for Improved Education, attributed the lopsided margin to the opponents' effective use of the charge that the tax credit was being pushed by "outsiders" and Mayor Marion Barry's claim that passage would mean a sharp increase in property taxes.

"I knew some time ago that we would have a really rough time of it," Pike said. "But I didn't think it would be as big a split as it was."

As soon as the precinct-by-precinct returns were released yesterday, various groups and political leaders began sparring over who deserved the credit for the resounding victory.

The city's labor unions, which had spearheaded the antitax-credit drive with telephone banks, sound trucks and radio ads, asserted that the sweeping numbers proved they had reestablished their political clout in the city and were a much stronger force to be reckoned with in the 1982 mayoral elections.

William H. Simons, president of the Washington Teachers Union, said yesterday that the defeat of the initiative "once again demonstrated the ability of labor to be an effective political force. It was through the unions that we really got the coalition together."

City Council Chairman Arrington Dixon, who served as chairman of the Save Our City committee against the initiative and engaged in more than 30 radio and television debates, said that "he hadn't focused yet" on what political advantage he may have derived.

But several of Dixon's colleagues on the City Council grumbled privately that Dixon had coopted the issue in order to gain political mileage for himself. Some were particularly incensed that, at a final rally against the initiative last Saturday in front of the District Building, Dixon was the only council member permitted to speak.

Meanwhile, council member Betty Ann Kane (D-At Large), who said she is forming a preliminary mayoral campaign committee in two weeks, claimed that she was every bit as active as Dixon in the fight against the initiative.

"If you look at the literature that everyone was handing out, it was all based on the fact sheet that I did back in May," Kane said. "I did a lot of radio call-in shows, I debated chief tax credit proponent Bill Keyes. And I also did a lot of talks at Catholic schools -- talk about walking into the lion's den."

But some council members said the overwhelming margin of the victory proved that no group or political leader can assert that their activities made a critical difference.

"I think everybody underestimates the basic intelligence of the people in this city," said council member John A. Wilson (D-Ward 2). "Most of the people get their news from the newspapers and television and this community realized that this was a disaster."

Wilson said opposition of private schools and the neutrality of Roman Catholic Archbishop James A. Hickey were "the turning point in the whole thing."

Council member David A. Clarke (D-Ward 1) said labor's claims had to be placed in perspective. "There's no question that labor was seen as a leading force and even if they are only seen as being a producer of the voters, that will give them an advantage in 1982," Clarke said. "But the fact is people in this town weren't going to vote for that anyway."