Such difficulties in implementing a Haig-Simons concept of income are of great practical significance. To the extent that income that comes in certain forms cannot be taxed, individuals’ decisions are biased in the direction of taking their income in those forms. Thus, for example, there is a bias in favor of capital gains (which are taxed only when the asset is sold) as opposed to dividend income (which is taxed as it is earned). Such biases create efficiency losses to the economy. Further, complicated rules are often needed to determine whether a certain type of income falls in a category that is favored by the tax system. Capital gains again provide a good example; it is not always obvious whether the return that an individual receives from a company is a dividend or a capital gain. Such complexity leads to substantial compliance costs.