The inaugural move, which Holder plans to announce today at a gay rights dinner gala in New York, marks a major gain for advocates of same-sex couples after the Supreme Court issued two rulings expanding gay marriage rights last year.
Under the new policy, same-sex couples will enjoy the privileges even in states that do not recognise their marriages, so long as they legally married in another state.
Among the key benefits the Justice Department will now ensure are extended to same-sex couples are the compensation fund for the September 11, 2001 attacks, as well as death and educational benefits for the surviving spouses of police officers and firefighters injured or killed in the line of duty.
Same-sex couples would also be held to the same legal standard as their heterosexual counterparts on matters such as how debts are handled in federal bankruptcy proceedings and visitation policies at federal prisons, as well as compassionate release or sentence reductions in certain cases.
Holder, who is due to deliver his speech at the Human Rights Campaign's gala at 0530 IST, plans to detail the new policy in a memorandum to employees tomorrow.