The Income has many definitions, depending on the context in which it is used. Definitions of income can be separated into four categories: income related to personal taxes, business INCOME STATEMENTs; aggregate income in an economy; and money versus REAL INCOME. In the U.S. personal-income tax system, the INTERNAL REVENUE SERVICE uses three definitions of income: total or gross income, adjusted gross income (AGI), and taxable income. Total income is, as the term suggests, money received by the taxpayer from all sources. For most U.S. taxpayers, total income is the sum of wage, salary, interest, and DIVIDEND income along with CAPITAL GAINs in a given year. Some taxpayers also have rents, royalties, distributions from INDIVIDUAL RETIREMENT ACCOUNTs (IRAs), refunds, alimony, business income, pensions, annuities, PARTNERSHIP income, and SOCIAL SECURITY benefits included in their total income. Adjusted gross income is total income minus a variety of deductions, including IRA contributions, student-loan interest, medical savings-account deductions, moving expenses, self-employment tax, health Simplified Employee Pension (SEP) payments, and alimony payments. Taxable income is adjusted gross income minus tax credits, including standard or itemized deductions and personal exemption allowances. Taxable income is the net amount of total income subject to U.S. personal income taxes. Business income statements, which can be quite complex, measure a firm’s income for its accounting period. Businesses compare revenue with expenses and allowances for DEPRECIATION to develop a statement of the company’s income. While accountants calculate a company’s income, the U.S. Department of Commerce estimates the country’s aggregate income, the total value of all claims against output. Aggregate income (GROSS DOMESTIC PRODUCT [GDP]) equals the sum of wages, rents, dividends, and PROFITs less net-factor income from abroad, plus capital consumption allowance and indirect BUSINESS TAXES. National income is GDP minus factor income, CAPITAL consumption allowance and indirect business taxes. Personal income is national income adjusted for income that is received but not earned and earned but not yet received. Finally, disposable personal income is personal income minus personal-income taxes, or what people have available to spend or save. Money income is income measured in dollars received in the current period of time, while real income is measured by the purchasing power of income received. Real income is money income adjusted for INFLATION. Economists use PRICE INDEXES such as the CONSUMER PRICE INDEX to compare the purchasing power of money income over time.