Allowing the appeal of the assesse the Court held that ; where the assessee has paid the income tax at source in the State of Sikkim as per the law applicable at the relevant time in Sikkim, the same income was not taxable under the IT Act, 1961 . It is a fundamental rule of law of taxation that, unless otherwise expressly provided, income cannot be taxed twice. A taxing Statute should not be interpreted in such a manner that its effect will be to cast a burden twice over for the payment of tax on the taxpayer unless the language of the Statute is so compelling that the court has no alternative than to accept it. In a case of reasonable doubt, the construction most beneficial to the taxpayer is to be adopted. While S. 5 of the IT Act would not be applicable, the existing Sikkim State Income Tax Rules, 1948 would be applicable. Thus, on the income, it would appear that Income-tax would be payable, under Sikkim State Income Tax Rules, 1948 and not under the IT Act. Since Sikkim is a part of India for the accounting year, there would appear to be, on the same income, two types of income taxes cannot be applied. On the issue of double taxation reference was made to , Laxmipat Singhania v. CIT (1969) 72 ITR 291 ( SC) (294) and Jain Brothers and Others v UOI (1970) 77 ITR 107 (SC). As regards other issue whether the income that is to be allowed deduction under section 80 TT of the IT Act is on ‘Net Income’ or ‘Gross Income’, becomes academic.( C A No. 4166 of 2006, dt. 19.04.2018)( AY. 1986-87)