Defense specialists are studying the possibility of using federal income tax and Social Security computer lists as a quick source of current names and addresses of draft-age men and women in a war mobilization.

They said Congress would have to grant an exemption from the Privacy Act to allow the Selective Service system and the armed forces access to the computerized information, even in an emergency.

The Internal Revenue Service and the Social Security Administration have merged computer tapes for tax purposes, a tax official said. These tapes could serve as a "built-in list of current names and addresses from which you could start to draw" for wartime military service.

Officials, who asked to remain anonymous, said this is one option being considered as an alternative to possible revival of peacetime registration urged by the Joint Chiefs of Staff and some senior civilian service leaders.

It was emphasized that Defense Secretary Harold Brown has made no decision on what steps to recommend to overcome acknowledged shortcomings in the country's ability to mobilize swiftly in a crisis.

Some officials believe authority to dip into the computer tapes only in a war emergency would improve mobilization readiness while avoiding what one source called the "hassle" of requiring millions of young men and women to register in person.