Payment in Lieu of Taxes Act of 1984 - Provides for payments in lieu of taxes to be made by the Administrator of General Services to local governments for certain property which is: (1) owned by the United States; (2) exempt from property taxation; and (3) located within the jurisdiction of the local government. Sets the amount of such payments at ten percent of the aggregate tax revenue that would be available if the property were subject to taxation.

Directs the General Accounting Office to submit a report containing recommendations on coordinating payments under this Act with existing Federal programs to avoid duplicative payments or windfalls and on the feasibility and constitutionality of subjecting Federal real property to full local property taxation.

Authorizes appropriations.