INCOME: ECONOMIC DEFINITION. Income has been defined as :—( ) "The wealth measured in money which is at the disposal of an individual or a community, per year or other unit of time"; (2) "The inflow of satisfactions from economic goods, estimated in money" (Seligman) ; (3) "Those incomings which are in the form of money, including `payments in kind.' " These definitions have some ambiguity. In general, the term is confined to those "satisfactions which are capable of being parted with, or are usually parted with, for money." For example, the satisfaction or economic value derived from living in one's own house is commonly expressible as an annual rental, and this is usually included in income, but an analogous satisfaction from contemplating one's pictures or using one's furniture is not. Again, periodicity is essential, and a year is the common basis, though the flow may be quite uneven, in fact, and even accruing unevenly over the year. Services performed for oneself which, if performed for others, would bring in an income are not usually included, e.g., painting one's own house, or a wife's domestic services. This is extended to exclude other mutual services within a group; e.g., a club or co-operative society. There is a field of difficult dis tinction from capital ; e.g., a series of profits from transactions which, taken singly, are regarded as capital transactions (sales of houses, lands or securities) may constitute an income in certain circumstances. And "net income" involves considerations of long period wastage in the producing agent—a coal-mine, or 99 years' lease, or a building. The term "national income" is subject to numerous special conventions.