The attorneys who work in the Exempt Organization Division at the Internal Revenue Service hardly look like a band of rebel bureaucrats eager to dictate social policy.

Director Joseph A. Tedesco and most of the division's top officials are government attorneys who have moved ahead by becoming specialists in minute and technical tax issues, not by advocating social change.

But the IRS's normally low-key exemption division has been spotlighted by President Reagan, who is concerned that it has been "determining national social policy all by itself," as he put it last week. The division's decade-old policy of denying tax-exempt status to segregated schools was challenged by the administration, in what has turned into one of the most embarrassing episodes of its first year.

During an interview, Tedesco refused to discuss Reagan's comments or the controversy over segregated schools. But the 25-year IRS veteran maintained that his division avoids making decisions on social policy. "Our job here is enforcing regulations, not deciding whether they are right or wrong," Tedesco said. "We actually have a very narrow focus."

Others in the division, however, said it is nearly impossible to issue tax rulings without getting into some social issues. About 25 percent of the rulings that the division makes each year set some sort of a social policy, they said.

Tedesco's division is responsible for deciding what nonprofit organizations qualify for tax-exempt status under sections 501(c)(3) through 501(c)(8) of the U.S. tax code. Currently, 846,433 organizations qualify for such status, but the total number of tax-exempt groups really is much larger, the IRS said. Churches are automatically tax exempt under the law and do not have to file tax-exempt forms although some of the lesser known denominations do to ensure the IRS recognizes them as a tax-exempt group.

Once an organization is designated as a tax-exempt group, it does not have to pay income taxes, nor Social Security and federal unemployment taxes for its employes. Contributions to most of the organizations also are considered to be tax deductible.

For 1978, the most recent figures available, taxpayers claimed $13.4 billion in itemized deductions for gifts to charitable organizations.

"Ninety-nine percent of these groups are extremely worthwhile organizations which were started to help the community," Tedesco said. The other 1 percent, he said, are trying to beat the tax system. Mail-order ministers, in particular, have been a headache for the division, he said, because it has to keep fine-tuning its regulations to be able to deny them status.

Tedesco's division has a budget of $26.2 million for fiscal 1982 and 776 employes in 16 district offices and at the IRS headquarters here. The Washington office has 115 attorneys who are responsible for interpreting the law and drafting revenue rulings (like the one that said segregated schools could not be considered tax exempt).

Last year, the Washington office wrote 50 revenue rulings, issued 374 technical-advice memorandums that answered specific questions from individual taxpayers, and directed the audits of 20,000 tax-exempt groups.

Of all the division's tasks, issuing revenue rulings is the most controversial. A ruling is a complete IRS project. It is proposed, drafted, written and approved by the IRS, officials explained. And once a revenue ruling is approved, the IRS considers it has the force of law until a federal court decides otherwise. That power is what irritated Reagan.

IRS officials contend they have to make revenue rulings to clarify tax statutes and resolve problems in difficult cases. For example, all that Sec. 501 (c) (3) says is, " . . . any community chest, fund, or foundation, organized and operated exclusively for religious, charitable, scientific, testing for public safety, literary or educational purposes . . . " can be declared tax exempt. Without its rulings, the IRS said it would be impossible for tax officials to determine which organizations are eligible under those broad categories.

"Trying to decide if the Boy Scouts or American Red Cross is a nonprofit organization is relatively easy," an IRS attorney explained. "How do you decide whether the Acme Clinic in Somewhere U.S.A. should be? That's the tough part."

The IRS decides by reviewing court decisions that dealt with clinics and by researching whether Congress mentioned clinics when it drafted the tax legislation. "When judging a tax-exempt request, we ask ourselves who is going to benefit from this and how will this service help the community," explained Edward Coleman, director of the technical branch under Tedesco. IRS also has to make sure that the organization is not violating any laws or public policies, Coleman said.

The types of organizations that have gotten tax-exempt status have changed though the years, Tedesco said. "There are a lot of organizations that wouldn't have qualified 20 years ago that now qualify because of recent court decisions," Coleman said. For example, nonprofit, public interest law firms and health maintenance organizations can now qualify.

The revenue rulings that angered Reagan were written after a 1970 court decision in a case filed by a group of Mississippi blacks against several white-only southern schools. At the time, the IRS opposed the lawsuit. Its attorneys said there was "no constitutional obligation" to use the tax laws to effect school desegregation. But the court disagreed. It said racial discrimination by private schools is "contrary to public policy" and therefore is incompatible with the tax exemption.

The IRS responded by issuing a series of revenue rules designed to deny tax-exempt status to segregated schools.