Personal saving is the amount left over from disposable personal income after expenditures on personal consumption, interest, and net current transfer payments. This amount is available to acquire financial assets such as bank deposits and mutual funds, to use towards acquiring a home, or to reduce liabilities by repaying principle on mortgages or consumer debt.

If expenditures on personal consumption, interest, and net current transfers exceed disposable personal income in a quarter, personal saving will be negative. This can occur because current income is not the only possible source of funds for consumption expenditures. Although spending must eventually fall back into line with income, households can spend more than their after-tax income for a time by withdrawing deposits saved in previous periods, by selling financial or tangible assets, or by borrowing. Indeed, an individual household’s saving is unlikely to be positive over the short run when it makes a major purchase of a consumer durable good such as an automobile, and even at the aggregate level, personal saving may fluctuate in periods when an unusually high number of households make such purchases.