Noncash welfare programs will total about $55 billion in fiscal 1982, will far outstrip cash payments, yet will still not reach more than two-fifths of the nation's poor, according to a new Census Bureau report.

The large noncash or in-kind programs, providing health care, food and housing assistance for the poor, were all started or greatly expanded in the 1960s; they have become the leading source of support for the poor and are based on means tests.

The report said that in 1980, 14.3 million households or more than one in six received help from one or more of the four major in-kind programs for the poor: Medicaid, food stamps, free or reduced-price school lunches and subsidized housing.

Of the 14.3 million, 7.9 million were households above the official poverty line (then $8,400 a year for a family of four). In most cases they were just above, in the category often called "near-poor."

The other 6.4 million households were below the poverty line and made up about 58 percent of all households in the U.S. (11 million) falling below that level.

Thus, only about three-fifths of all poverty households actually received any in-kind benefits in 1980 and two-fifths got none. About 40 percent of the poverty households in the country got food stamps, 40 percent had one or more members eligible for Medicaid and 24 percent lived in subsidized housing. About 65 percent with school-age children were beneficiaries of the school lunch program.

Officials said there are a number of reasons why people with below-poverty incomes do not get in-kind benefits. Some, although below the poverty line, still are not poor enough to meet state eligibility cutoffs for programs like Medicaid.

Others have little income but may have a few thousand dollars in countable assets and therefore fail to qualify. For example, a family can have no cash income at all yet be ineligible for food stamps if it has $1,500 or more in cash assets. Others are eligible only for small benefits that they feel are not worth the effort of tangling with welfare departments. Still others are unaware they are eligible. And single people or childless couples are ineligible for Medicaid regardless of how poor they are are, unless aged or disabled.

While millions of poor households failed to get any in-kind benefits, some 7.9 million households above the poverty cutoff did get at least one. Officials said some of these people were destitute when they received the aid but later got jobs and had total income for the year that put them over the poverty line.

In other cases, however, it has been deliberate government policy to provide benefits to those a bit over the poverty cutoff, partly on grounds that they also are in need by most normal standards, and also because they would be discouraged from seeking work if they knew they would lose all welfare benefits once they crossed the poverty line.

The study showed that about a quarter of all black households got food stamps, half got free or reduced-price school lunches, a quarter lived in subsidized housing and more than a quarter were eligible for Medicaid; among single-parent households headed by a woman, 30 percent got food stamps, 45 percent got reduced-price lunches, nearly a quarter got housing assistance and about one third were eligible for Medicaid. For all households, the percentages were about one-third these.

The study showed that in a small percentage of cases, households with substantial income were getting in-kind benefits, presumably on the basis of special needs, meaning they were very large families or families with heavy medical and work expenses. Thus, 328,000 of the nearly 7 million households getting food stamps had income of $20,000 or more; 661,000 of 5.5 million getting below-cost school lunches had income above that level; 96,000 in subsidized housing had income above $20,000; and 1 million of the 8.2 million households on Medicaid had incomes above $20,000.

The study also shows that "pyramiding" of benefits--collecting benefits from many programs simultaneously--is not as common as often supposed. Of the 14.3 million households (poor and non-poor) getting in-kind benefits in 1980, 8 million got only one type of benefit, 3.7 million received two kinds of benefits, 2 million received three kinds and only 462,000 received all four.