No import duty shall be paid by the United States and contract prices shall be exclusive of duty, except when the administrative cost compared to the low dollar value of a contract makes it impracticable to obtain relief from contract import duty. In this instance, the contracting officer shall document the contract file with a statement that—

(a) The administrative burden of securing tax relief under the contract was out of proportion to the tax relief involved;

(b) It is impracticable to secure tax relief;

(c) Tax relief is therefore not being secured; and

(d) The acquisition does not involve the expenditure of any funds to establish a permanent military installation.