The Housing and Urban Development Department has officially deputized the nation's 3,000 public and subsidized housing agencies to make sure only citizens or legal U.S. residents live in the 2.9 million federally subsidized housing units nationwide.

Anyone moving into subsidized housing or being recertified as a tenant must show proof of citizenship or legal residence, in the form of a passport, birth certificate, naturalization certificate, voter registration card, draft registration form, alien registration card, or a variety of other documents. As a last resort, a tenant can have a third party swear to his citizenship. It is not sufficient for tenants themselves to take such an oath.

Some housing authority managers are not happy with their new role, in part because of the paperwork involved, in part because of potential manager-tenant antagonisms. "Administratively this is going to be a very serious burden," said Apolonio Flores, director of San Antonio's housing authority. " . . . They're trying to make the housing authority into a police force." Some 65 percent of the 15,000 families in San Antonio public housing are Hispanic.

In the final rule published a week ago, HUD said "a voluntary disclosure process may be ineffective because such disclosures are difficult to verify. The use of [personal oaths] affords little protection . . . because they can be easily falsified and the threat of criminal prosecution may be of little concern to those aliens facing possible deportation if their true situations were known." The rule becomes effective sometime next year, when Congress has been in session 30 days.