Net domestic income, commonly called net domestic product or NDP, is the value of all goods and services produced within a country over a given period. This value is calculated as gross domestic product, or GDP, minus capital depreciation.
GDP broadly measures a nation's economic performance; it's the sum of consumption, government expenditures, investing and exports minus imports. To arrive at NDP, take the GDP and subtract capital depreciation; this is called the capital consumption adjustment. NDP provides an indication of the obsolescence of capital assets and how much the government has to spend to maintain economic production. The U.S. Department of Commerce releases GDP information on the last business day of each quarter.