Congress keeps enacting more and more tax breaks for special-interest groups, but almost never reviews them to see whether they ought to be discontinued, Common Cause said yesterday.

In an 80-page study, the public affairs lobbying group said that between 1971 and 1976 Congress failed to take a single publicly recorded vote on whether to renew dozens of existing tax breaksworth a cumulative $161 billion.

It charged that when congressional tax-writing committees did hold hearings on tax break legislation, the bulk of the testimony "came from witnesses with direct financial interests" in continuing or enlarging the breaks.

David Cohen, the organization's president, particularly singled out the Senate Finance Committee, which he said recommended 25 new tax breaks during the period worth a cumulative $72.7 billion and voted to enlarge 39 others.

Cohen called for the Finance Committee "one of the biggest and least-responsible spenders of government tax dollars." He urged taxpayers to "start paying a lot closer attention" to the way the tax-writing panels operate.

The series of conclusions was contained in a detailed report on the handling of tax-break legislation by Congress during the 1971-76 period. The document, entitled "Gimme Shelters," was timed to reach Sunday newspapers.

Publication of the report at this time was regarded as ironic. John W. Gardner, founder and former chief executive officer of Common Cause, has been actively lobbying for passage of a big new tax break to aid charities, estimated to cost $3.2 billion a year.

Jack Moskowitz, another former Common Cause official who now is a lobbyist for the United Way, also has been active in that effort. Common Cause is not involved in supporting the proposal, which is being opposed by Treasury as an unnecessary giveaway of tax revenues.

The Common Cause study received support from from Sen. Edward M. Kennedy (D-Mass.), a leading "tax reform" proponent in Congress. Kennedy called the document "an important milestone in the effort to eliminate . . . abuses."

There now are more than $120 billion worth of tax breaks on the books, including provisions such as the one allowing taxpayers a deduction for the interest they pay on home mortgage loans.

As is the case with most legislation, Congress has not regularly reviewed these measures to decide whether they should be continued. However, the lawmakers cut back some tax breaks in 1969 and 1976.

The Common Cause study made these points:

Congress enacted 16 new tax breaks between 1971 and 1976, repealed two others and decided not to renew three more.

Almost 90 per cent of existing tax breaks are written permanently into the law, and do not require periodic renewal.

Congress has considered so-called "sunset legislation" to require regular review of spending programs, but has not enacted any concerning tax laws.

Of the testimony before tax-writing committees during the period, 45 to 65 per cent came from private commercial interests and 4 to 12 per cent from so-called "citizens' groups."