In terms of future research on the taxation of socialist economies, real world complexity has a number of implications. Future research must take account of the special characteristics of the socialist economy, as well as the complexity of its tax system. These special characteristics can be summed up briefly. The socialist economy is centrally planned, and the means of production are owned collectively. In practice, the taxation of real world socialist economies is much more complex than the four tax model suggests. The four taxes model: turnover tax, wages tax, capital charges, and profits tax. In spite of the limitations of public finance theory discussed so far, it is possible to obtain some general indication of directions for future research in each of our four taxation areas. Wage fund tax is a tax which is apparently of supply-side importance, through its effect on work effort and incentives.