In 1975 Marilyn Voigt, a Chevy Chase housewife, decided to go into analysis. The process, she thought, would be particularly helpful to her career as a clinical social worker, a job she had just returned to after a 13-year hiatus. It also would help alleviate minor problems of anxiety and depression.

When it came time to fill out their 1975 federal income tax, Marilyn and her husband Harry listed $5,945 in business expenses. The money was not spent on college courses; it was fees paid to Marilyn's private psychiatrist. The therapy, they reasoned, was educational.

The Internal Revenue Service disagreed.

Marilyn Voigt, the government claimed, was using the therapy to qualify herself for a better paying job as a clinical social worker. Therefore, her fees did not fall under the educational category of business expenses. The IRS also said the fee was not a medical expense since treatment was not her primary aim.

Is lying on a couch five times a week and revealing unconscious conflicts educational. The Voigts believe it is. So did a U.S. Tax Court judge who ruled in their favor last month, saying Marilyn's psychoanalysis "improved the diagnostic and treatment skills required in her employment."

The unprecedented ruling, according to one IRS official, is expected to open a floodgate of similar claims by teachers, ministers, probation officers and psychiatric nurses who may benefit from the therapeutic tax break.

The IRS says that no decision has been made whether to appeal the case, which could be a landmark decision affecting the entire mental health profession.

Up to now, an IRS spokesman said, only practicing psychoanalysts were legally permitted to deduct the cost of their own analysis as a business expense. Under that category, the entire amount of the expense is tax deductible. As a medical expense, the taxpayer may only deduct that portion of the bill that exceeds 3 percent of his adjusted gross income.

According to Harry Voigt, the couple saved $1,500 in income tax by claiming the psychiatric fees as a business expense. "Obviously, we're very pleased," he said. "Clinical social workers have now been recognized in the same category as psychiatrists."

But a check with area accountants revealed that psychiatrists, psychologists and even social workers have been claiming the tax break in years past, perhaps illegally.

"We've done it for years," said one accountant who regularly handles tax returns for mental health professionals. "No one ever asked."

IRS spokesman Al Golato, however, said, "If I were an agent in the field, I would disallow it."

Marilyn Voigt, now working as a co-therapist with a Washington psychiatrist, said yesterday, "From a professional standpoint, I feel it [the ruling] is helpful to social workers."

A clinical social worker who has undergone psychoanalysis receives more referrals from psychiatrists and other mental health professionals, according to the ruling. However, it is not a requirement for certification.

"She basically did it to get ahead in her profession," said Harry Voigt, speaking of his wife's psychoanalysis which she is still undergoing.

Audrey Thayer Billett, chief psychiatric social worker at George Washington University, said that seven of the school's nine social workers have undergone psychoanalysis or psychotherapy.

She did not know whether they had deducted the cost as a business expense. "I consider it part of their education experience," Billett said. "It's definitely a plus, an additional qualification."

The issue highlights the strenous lobbying efforts by social workers in America to gain the same professional recognition long afforded psychiatrists, and recently won by psychologists.

According to the National Association of Social Workers, there are currently more than 400,000 members of the profession. Of the four mental health areas, social workers make up 50 percent of the labor force and provide about 60 percent of the mental health care in America. More than half of all community mental health centers in the nation are run by clinical social workers, whose median income is $17,500 a year. More than 65 percent of all social workers are women.

Despite these statistics, only 24 states -- including Maryland and Virginia -- license social workers. The District of Columbia does not.

Miles Johnson of the National Association of Social Workers said yesterday the tax court ruling "will encourage social workers to use therapy. We like that."

A spokesman for the American Psychiatric Association said the matter had more to do with taxes that psychiatry.

"It's a definite benefit for anyone getting into analysis to enhance their job skills," said Harry Voigt. A Washington lawyer who handled his wife's case, Voigt also will be able to deduct the cost of fighting the IRS in court.