disposable income

This term is primarily used in economic, financial, and policy contexts to distinguish between gross earnings and the actual purchasing power of a consumer. It carries a neutral, technical tone and is common in discussions regarding taxation, cost of living, and consumer behavior.

Because it refers to a specific financial aggregate, it is treated as an uncountable noun. You cannot refer to "disposable incomes" when discussing the general economic concept, though you may refer to the disposable income of different groups in a comparative sense.