We extend the WACC approach to a tax system having a firm income tax and a personal income tax of the investor as well. We use an artificial tax system incorporating most of the G-7 national tax codes as for example the classical or the imputation systems.

Introduction: A Stochastic Approach to Discounted Cash Flow -- Basic Elements: Cash Flow, Tax, Expectation, Cost of Capital, Value -- Corporate Income Tax: WACC, FTE, TCF, APV -- Personal Income Tax -- Corporate and Personal Income Tax -- Proofs -- Sketch of Solutions.