The largest provider of health insurance benefits to federal workers will cut its payments for nonhospitalized mental care in January at the same time it introduces a broad dental program.

For those enrolled in the Blue Cross/Blue Shield medical program, benefits will be reduced from 80 percent of the cost of the doctor's bill to 70 percent for those covered by the more liberal of its two supplemental benefits options, and from 75 to 60 percent of the less liberal option.

Thus, reimbursement for a $50 visit to a psychiatrist or clinical psychologist will be cut from $40 to $35 under the more liberal option. For those under the less liberal plan, the reimbursement will be cut from $37.50 to $30. Beneficiaries must pay the balance.

Blue Cross and Blue Shield, which serve 285,000 federal employes in the Washington area and 1.9 million nationally, reached agreement on the mental health reimbursement reductions in negotiations with the U.S. Office of Personnel Management (OPM) that were concluded in September.

A summary of changes in all 121 health programs available to government workers -- many of them in localized geographic areas or in specific employe groups -- will be distributed to agencies by Nov. 10, the start of a four-week period in which employes will be permitted to change from one insurance carrier to another. The deadline for making changes is Dec. 5.

Dr. Howard Kaiser, a Bethesda psychiatrist and president of the Washington Psychiatric Society, said the change will discriminate unfairly against psychiatric patients, especially dependents of lower-ranking government workers.

"I can't give a number, but there are a great many, including children, who are going to be penalized for having mental problems," Kaiser said. "That is what it really amounts to, that it singles out a single medical specialty in an arbitrary way."

A study by the society last March showed that nearly 46 percent of the patients of its 1,000 member psychiatrists were covered by federal health insurance programs. Of that number, nearly 84 percent were covered by Blue Cross/Blue Shield. The second largest carrier, Aetna Insurance, provided coverage for about 6 percent.

"I guess the easiest way to answer [criticisms of the mental health payments reduction]," said Kenneth Lease, chief of government-wide health programs for OPM, "is that it was an acceptable tradeoff for the dental benefits we wanted. We think most employes would think so, too."

Under the revised program, Blue Cross and Blue Shield will pay the full costs of many common dental treatments, including fillings, extractions, cleaning and emergency services. Benefits are not subject to a deductible or to annual maximums.

As part of the revised package, Blue Cross and Blue Shield added coverage for alcoholic rehabilitation. Two four-week stays at a rehabilitation center may be reimbursed during an insured person's lifetime. There is no change in the full reimbursement for inpatient psychiatric care in a Blue Cross member hospital.

James N. Gillman, the Blue Cross/Blue Shield vice president for federal programs, said the new program changes will result in benefits being paid to a broader segment of those enrolled under its insurance programs.

Lease, the federal health program chief, said negotiations did not deal with accusations often made informally that federal workers abuse or overuse mental health benefits -- a point that Dr. Kaiser, the psychiatric society president, described as inaccurate and unwarranted. He said a study conducted by the society earlier this year contradicts such contentions.

The Washington area has the second-highest concentration of psychiatrists in the nation, exceeded only by New York City.

Overall, the changes negotiated by the government with the insurance carriers will result in a 16.8 percent increase in U.S.-paid premiums. Premium costs will go up an aggregate of $635 million, of which about $265 million will be paid by the covered employes, and about $375 million by the government.

For employes covered by Blue Cross/Blue Shield, individual premium payments will rise by 13.6 percent. Increases during each two-week period will range from 40 cents for an individual enrolled under the least liberal benefit option (for a total premium of $2.46) to $3.65 for a family enrolled under the most liberal option (for a total premium of $30.52).