Executive Rule No. 6 establishes the mandatory procedure for income tax retention concerning foreign Incorporated Bodies. It obligates all ministries, public and private entities, and natural persons to retain 5% from the value of any contract, agreement, or transaction. The Rule stipulates that these retained funds are held in trust for the State Public Treasury. Release of these amounts is contingent upon receiving a formal letter or certificate from the Tax Department. The Rule also mandates reporting these retentions to the Tax Department.