Kathy and Wendell Coates are saving for a down payment on their first home, but the amount of money they can set aside by next spring may not be enough. Their dilemma is shared by thousands of other black families who find it difficult, if not impossible, to make the leap from renting to owning a home.

Harvard University's Joint Center for Housing Studies reported recently that 3.5 percent of black renters in the United States are able to buy homes now, compared with 16.9 percent of whites. Lower incomes than whites and racial discrimination in buying and borrowing are the major barriers to black homeownership, researchers said.

The percentage of blacks locked out of the housing market has changed little in 30 years, said William C. Apgar Jr., acting director of Harvard's Joint Center for Housing Studies, which issued the report.

A major cause is blacks' lack of money or property to pass on to their children, a problem that perpetuates itself, he said. Homeownership is "a wealth accumulation vehicle," an important source of funds and savings for most white families. Many white purchasers, especially those buying their first homes, get help from their families through gifts, loans or inheritances.

The Harvard report said 13.6 percent of the total 29 million renters of all races in the United States could qualify for a mortgage to buy "the typical starter home in 1986," the latest year for which figures were available. The 3.5 percent of black renters who can buy assumes they can make a down payment of 10 percent of the mortgage. If they had to make a 20 percent down payment, the amount most banks require, only 1.5 percent could purchase a house, according to the Harvard study.

Renters, particularly those in high-cost areas like the Washington metropolitan region, generally have a hard time saving money, analysts said.

"With rent as high as it is now, it's taking all {of black renters'} money and they can't save for the down payment and closing costs. The odds are really against you," said Alyce Payne, a real estate agent who is black.

The median income of black families nationally is $19,329 -- half the $33,915 figure for whites as of March 1989, the Census Bureau said. The most recent report of family net worth -- its savings and major assets minus debts -- shows a much bigger gap between whites and blacks. The net worth of white families was nearly 12 times that of blacks when the report was issued in 1984 -- $39,135 for whites and $3,397 for blacks.

"It's very difficult, if not almost impossible, for blacks to make that transition" from renting to owning, agreed Leroy Hubbard, a housing activist and president of the Metropolitan Washington Housing Association, a policy and research organization.

In many cases they must "go out and borrow money, and work two or three jobs just to qualify for a loan. It's very hard for them to become a part of the American dream and, believe me, they want to," he said.

The Coates family, including the couple's two children, lives in a two-bedroom apartment in Landover, paying $555 a month in rent plus utilities. With a combined income of about $35,000 from her job as a secretary in the District and his work at a Circuit City store, their earnings are higher than the median family income for the southern United States. The Census Bureau, which collects these statistics, includes the Washington area in the South.

Although its income is above the median, Kathy Coates said, her family lives "from paycheck to paycheck" much of the time. "It seems like when we have extra money {an unanticipated need} comes up."

The couple said they believe they can save about $1,000 by next spring, and they hope to get some financial assistance from Prince George's County. But a county spokesman said that under programs available now, the Coates family would need at least $2,500 in cash and perhaps $5,000 in order to buy a house.

Several local governments help moderate-income families buy their first homes, with programs that have attracted national attention and praise in some cases. Despite these efforts, blacks here have a harder time than whites coming up with the cash needed and they often encounter bias, according to buyers, government agencies and real estate professionals.

Low- and moderate-income black families in the District of Columbia can qualify for the city's Home Purchase Assistance Programs, said Shealia Tyson, president of the Washington Real Estate Brokers Association, an affiliate of the predominantly black National Association of Real Estate Brokers. Many of Tyson's clients are renters trying to buy their first homes and could not put together enough money for a down payment without help, she said.

John Relman, a lawyer with the Washington-based Lawyers Committee for Civil Rights Under Law, said he believes that "racial discrimination is pervasive in lending and real estate practices" in the Washington area.

However, "there is very little hard and fast data" to show that banks reject loan applications for racial reasons, said Deborah Goldberg of the Center for Community Change here. There are "patterns you can draw implications from," she said.

A series of studies over the past decade, including a report issued by D.C. Banking Superintendent Edward D. Irons last May, indicate there is discrimination, she said.

Irons's report said six Maryland and Virginia banks that acquired District lending institutions had not made the amount of investments in economically depressed neighborhoods that they had promised.

The report also said the amount invested in housing between 1987 and 1989 in each city ward was lowest in the wards where the percentage of blacks and other minorities was highest.

The Washington Area Bankers Association challenged Irons's findings, saying that more than $100 million had been invested in those areas in the past five years.

"When you look at patterns, and the neighborhoods that haven't gotten loans for years and years, how else can you explain those patterns, if there is not discrimination happening in some shape or form," Goldberg said.

"Minorities are not told about creative financing, and they are not told about government programs to assist first-time home buyers," said Linda Hardy, a real estate agent and chairman of the Northern Virginia Community Housing Resource Board. "The overriding factor ... is that minorities are not given the type of information they need."

"Sometimes what may go on is what I would call pre-screening," Goldberg said. "If you talk to bank regulatory agencies' people, they rarely if ever find hard evidence of lending discrimination."

A reason for this may be that prospective buyers who are from minorities are discouraged from filing applications, she said. Bank officials may be courteous and helpful while making clear the loan is not likely to be approved.

Testing for discrimination in the rental and sale of housing has been carried out in past years by the Fair Housing Council of Greater Washington and by local governments. Most have been tests of rental housing and have found that discrimination occurs more than 50 percent of the time in some parts of the metropolitan area.

One of the most recent testing projects, however, was sponsored last year by Arlington County's Office of Housing. It found four instances of bias in 25 tests, according to the report. Black and white testers, who are alike in all characteristics except race, visit the same real estate offices, usually only an hour or two apart.

One test showed that a white male real estate agent encouraged a black to buy a house in South Arlington and told a white that buying a home in South Arlington was not a "good idea" because it "was a black area and wouldn't suit you," the report said.

In another case, a white tester was told she would be able to buy a $97,200 house while the black, who said her income was $1,000 higher, was told she would qualify for a $75,000 home.

Discrimination, along with lower incomes and less savings, have kept the number of black homeowners low for generations, the Harvard study said. Only 45 percent of black households owned homes in 1986, compared with 70 percent for whites, and the value of blacks' homes lagged those of whites.

"Nevertheless, black homeowners still managed to accumulate significant wealth {$38,321} -- at least relative to black renters," the report said. Wealth is the term researchers use for the value of savings and assets such as homes and automobiles minus debts.

Blacks need help to catch up, Apgar said. "Some people say we don't need affirmative action," Apgar said. "That doesn't make sense where people don't start out equally."

Meanwhile, the Coateses' dream of moving from their apartment and buying a house lives on. Wendell Coates said he is soon going back to work on the weekends. "I'd like to make a little extra money," he said. "We'd like to get out of here. That's the main thing."