The Internal Revenue Service has changed its rules to halt most of the "voter education" literature that is the stock in trade of the country's tax-exempt organizations.

In a 1978 action that affects elections for the first time this year, the IRS decided that most traditional voters' guides, candidate questionnaires and issue scoreboards are political tracts in disguise. Since groups that receive tax-deductible funding are prohibited from engaging in any political campaign activity, the voter education material is now banned too, on pain of loss of tax-deductible status.

The result, according to Joel Thomas, general counsel of the National Wildlife Federation, is that "the good guys" who support the nation's mind-boggling range of special interests are going unthanked for their efforts and are beginning to think the interest groups are ungrateful.

For example, a senator who wants to vote to expand wilderness areas in Alaska this week can expect to be blasted in oil industry trade association missives to its members, since that kind of association is permitted some political activity. But the National Wildlife Federation won't be able to tell its 3.5 million members about it, Thomas said.

"These guys turn on us and say, "Why can't you tell your people what we've done for you? I'm being killed and you're not helping,'" lamented federation vice president Oliver Hauck. "Their eyes glaze over when we try to explain the technical reasons."

The IRS first tried in early 1978 to ban all voters' guides, but revoked that after a major outcry led by the League of Women Voters. In June 1978, a new ruling softened the ban to allow publication of voters' guides on "major legislative issues" as long as they contain no editorial opinion or implication of approval or disapproval.

But questionnaires that concentrate only on "a narrow range" of issues were forbidden. That effectively prevents any special interest group from evaluating the positions of politicians and candidates on its favorite issue or issues.

And so it should, said Howard Schoenfeld, special assistant for exempt organization matters at IRS.

"Why would an organization distribute a voters' guide on selected issues among the electorate during a campaign, if not to influence the voters?" he asked. "If there's a wide range of issues it's okay . . . it depends on the facts and circumstances of each case."

The ban on direct or indirect participation or intervention in political campaigns is for "charitable and educational" groups only and was tacked onto another bill in 1953 as an amendment on the Senate floor by the then minority leader, Lyndon B. Johnson.

Allegedly irked by opposition to his 1952 reelection from one nonprofit group, he got the measure passed with no committee scrutiny or floor debate. This leaves regulators very little legislative history for guidance on just what the ban means.

While it clearly prohibits endorsements or denunciations, the ban was interpreted until 1978 to allow the "educational" newsletters that monitor congressional action on a group's concerns, as long as readers were allowed to draw their own conclusions.

"But now we're not allowed to tell our grass-roots people whom they can thank," said Dr. Elvis Stahr, counselor and past president of the National Audubon Society. "It's hard for our people who are interested in issues to know if they're accomplishing anything or not when they write in."

The United Church of Christ has appealed the 1978 ruling to the commissioner of internal revenue and will take the issue to court if the appeal is denied, according to UCC legislative counsel Barry W. Lynn. "Our constitutional rights haven't just been chilled, they've been frozen," he said.

The ruling is ambiguous in several respects, he said. It eliminates "narrow" questionnaires but does not define the term."How narrow is narrow?" asked Maudine Cooper, Washington vice president of the National Urban League.

The Urban League, she said, has always published "the records of everyone, on the issues we're concerned with, and we'll keep doing it until we get an interpretation of the word 'narrow.'"

That could mean trouble with the IRS. In its 1978 ruling, the agency disallowed an unnamed conservation organization's voters' guide as too narrow, even though it covered a range of environmental questions.

What really irks the groups concerned is that industry trade associations can use part of their money for politicking while the nonprofit groups cannot.

Business leagues, chambers of commerce, real estate boards and boards of trade as well as trade associations like the National Coal Association and the Chemical Manufacturers Association all live like the smaller groups on tax-deductible dues from their member businesses.

But unlike the educational groups, the business groups may receive some nondeductible funding, pay taxes on it and use it for political activity like naming their friends and enemies.

Taxwise, the two kinds of groups are equal, said Schoenfeld, pointing out: "In no case can a taxpayer get a deduction for payments to any association for political activity," over the $50 individual contribution that everyone may deduct, he said.

Trying to explain this difference to members of Congress is further complicated by the difficult distinction between lobbying for legislation, which the educational groups may do, and political campaigning, which they may not do. That means, according to the IRS, that the groups may not inform their members whether the lobbying changed anyone's mind for that would be endorsing candidates' views.

The constitutionality of the ban on charitable groups' political acts has been upheld several times in court, but Lynn of the United Church of Christ said his group's argument would be different.

It would focus, he said, on the provision of free speech rights to trade associations while the charitable groups are denied such rights.