This study was undertaken by the writer because there are cases and situations when the provisions of the Tax Code affecting interest expense are either interpreted with extreme liberality as to defeat the purpose of taxation for raising revenues or with such rigid strictness as to make taxation practically confiscatory. Concretely, the problems to be explored in this study are the following: (1) Are supporting papers necessary for the deductibility of interest expense? (2) Should interest incurred on borrowed money for the purchase of government or tax-exempt securities be allowed as a deduction from gross income? (3) Should the records or books of accounts of banks be open for examination for purposes of checking interest deduction? (4) Should interest payment for delinquency taxes be allowed as a deduction from gross income? and (5) Should the registration of non-resident foreign corporations be allowed when the clear intention is merely to evade taxes on their interest income?