While per capita gross domestic product is the indicator most commonly used to compare income levels, two other measures are preferred, at least in theory, by many analysts. These are per capita Gross National Income (GNI) and Net National Income (NNI).

Disposable income, as a concept, is closer to the concept of income generally understood in economics, than either national income or GDP. At the total economy level it differs from national income in that additional income items are included, mainly other current transfers such as remittances. For countries where these additional items form significant sources of income the importance of focusing on disposable income in formulating policy is clear. For OECD countries the differences between national and disposable income at the total economy level are typically insignificant. But another very important difference between national income and disposable income concerns the allocation of income across sectors. At this level significant differences arise. In the main these reflect the reallocation of national income: from corporations and households to government, on account of income taxes; from households to government to reflect social contributions; and, from government and corporations to households to reflect social benefits other than social transfers in kind. It is mainly this reallocation of income that brings the concept of income closer to the economic concept. Indeed, ignoring, for simplicity, changes in net worth that arise from capital transfers or holding gains say, disposable income can be seen as the maximum amount that a unit can afford to spend on consumption goods or services without having to reduce its financial or non-financial assets or by increasing its liabilities.

As described in earlier sections, measures of income, such as national or disposable income are generally preferred, in theory, to GDP, in analyses of well-being both in nominal and real terms. However there are some specificities related to the calculation and associated interpretations of real income, as opposed to real GDP say, that are worth mentioning.

The purpose of saving is to increase future resources available for consumption and to protect against unexpected changes in income. Saving in its simplest terms is very similar to the concept of saving commonly used by the man on the street. It reflects the amount of disposable income that remains after final consumption expenditures, and that is invested – be that in financial assets, such as bank deposits or shares, or non-financial assets, such as real estate. Its importance is therefore paramount in many areas such as: analyses of the sustainability of consumption patterns; or the scope of governments to stimulate demand or raise taxes. Government saving is also an important indicator in a budgetary context. The “Golden rule”, for example, that government saving should be zero over the course of an economic cycle is often set as a fiscal objective.

Household saving is the main domestic source of funds to finance capital investment, which is a major impetus for long-term economic growth. Household saving rates vary considerably between countries because of institutional, demographic and socioeconomic differences. For example government provisions for old-age pensions and the demographic age structure of the population will all influence the rate at which populations save (older persons tend to run down their financial assets during their retirement to the detriment of saving). Equally the availability and price of credit, as well as attitudes towards debt, may also influence choices made by individuals regarding whether to spend or save.

Net lending/borrowing is one of only two balancing items in the SNA where the reference to “net” is not in juxtaposition to “gross”: in other words it is not in reference to lending net of depreciation. If it is positive it is described as net lending and if negative, as net borrowing. It reflects the amount of financial assets that are available for lending or needed for borrowing to finance all expenditures – current, gross capital formation, non-produced non-financial assets, and capital transfers – in excess of disposable income. Its importance as an economic concept is best illustrated by the fact that it forms one of the two Maastricht excessive deficit criteria used by the European Commission to assess the soundness and sustainability of public finances.