Most Americans think there are too many loopholes in the income tax laws yet they approve most provisions that cut taxes, according to a public opinion survey released yesterday.

The survey by the Roper Organization, Inc., for the tax return preparation firm H & R Block, Inc., found that tax loopholes to most people "mean some obscure tax rules known only to the most sophisticated financial wizards, certainly not those familiar deductions and allowances on the tax return forms the average taxpayer is familiar with."

But suggestions that tax loopholes be closed were resisted when the specific exemption or deduction was mentioned.

The study found that "a majority of the public condemns the income tax system as unfair to most people." More than half of all taxpayers characterized ther own income taxes as "excessively high," the survey said, but low and moderate income persons tended to overestimate the percentage of their income that goes for taxes and to underestimate the amount wealthier people pay.

Those surveyed said they were so confused by the tax return forms that 54 per cent relied on professionals to complete them, while another 23 per cent relied on knowledgeable relatives or a spouse to fill them out. But the taxpayers polled gave a low priority to simplification.

Burns Roper, head of the polling company, told a news conference that only one in four said simplification of tax forms should be a top priority of government, while 47 per cent labeled unemployment the chief problem.

Roper said a primary conclusion from the survey is that President Carter will have a "difficult" time selling tax simplification to the public, especially if it means an end to deductions for home mortgage interest and local property taxes.

The Roper researchers concluded that "a good deal of the reason behind the indictment of the income tax system as 'unfair to most' appears to be gross misunderstanding of, and lack of information about, how the income tax system works.