Taxes on income and capital defined broadly to include gains, wages, and substitute taxes; mutual notification required. The Convention applies to taxes on income and on capital imposed on behalf of a contracting State or its subdivisions, encompassing taxes on total income or capital and on elements thereof, including gains from alienation, wages or salaries paid by enterprises, and capital appreciation. It lists the principal existing covered taxes in each contracting State and extends to identical or substantially similar taxes enacted after signature, with a requirement that competent authorities notify each other of significant changes in their taxation laws.