General Principles of Philippine Income TaxationIncome –It means the gain derived from capital, from labor or from both combined including profits gained from dealings in property or as well as any asset clearly realized whether earned or not.It is a tax on the net income or the entire income received or realized in one taxable year. It is levied upon corporate and individual incomes in excess of specified amounts less certain deductions and/or specified exemptions in case permitted by law.Coverage of Philippine Income Taxation 1)A citizen of the Philippines residing therein is taxable on all income derived from sources within and without the Philippines.2)A non-resident citizen is taxable only on income derived from sources within the Philippines.3)An individual citizen of the Philippines who is working and deriving income from abroad as an overseas contract worker is taxable only on income from sources within the Philippines.4)An alien individual whether a resident or not of the Philippines is taxable only on income derived from sources within the Philippines.