A value added tax (VAT) is a form of consumption tax. From the perspective of the buyer, it is a tax on the purchase price. From that of the seller, it is a tax only on the value added to a product, material or service, from an accounting point of view, by this stage of its manufacture or distribution. The manufacturer remits to the government the difference between these two amounts, and retains the rest for themselves to offset the taxes they had previously paid on the inputs.

The value added to a product by a business is the sale price charged to its customer, minus the cost of materials and other taxable inputs. A VAT is like a sales tax in that ultimately only the end consumer is taxed. It differs from the sales tax in that, with the latter, the tax is collected and remitted to the government only once, at the point of purchase by the end consumer. With the VAT, collections, remittances to the government, and credits for taxes already paid occur each time a business in the supply chain purchases products.

In economics, the difference between the sale price and the production cost of a product is the value added per unit. Summing value added per unit over all units sold is total value added. Total value added is equivalent to Revenue less Outside Purchases (of materials and services). Value Added is a higher portion of Revenue for integrated companies, e.g., manufacturing companies, and a lower portion of Revenue for less integrated companies, e.g., retail companies. Total value added is very closely approximated by Total Labor Expense (including wages, salaries, and benefits) plus "Cash" Operating Profit (defined as Operating Profit plus Depreciation Expense, i.e., Operating Profit before Depreciation). The first component (Total Labor Expense) is a return to labor and the second component (Operating Profit before Depreciation) is a return to capital (including capital goods, land, and other property). In national accounts used in macroeconomics, it refers to the contribution of the factors of production, i.e., land, labour, and capital goods, to raising the value of a product and corresponds to the incomes received by the owners of these factors. The national value added is shared between capital and labor (as the factors of production), and this sharing gives rise to issues of distribution.

Paul Robin Krugman ( /ˈkruːɡmən/; born February 28, 1953) is an American economist, Professor of Economics and International Affairs at the Woodrow Wilson School of Public and International Affairs at Princeton University, Centenary Professor at the London School of Economics, and an op-ed columnist for The New York Times. In 2008, Krugman won the Sveriges Riksbank Prize in Economic Sciences (informally the Nobel Prize in Economics) for his contributions to New Trade Theory and New Economic Geography. According to the Nobel Prize Committee, the prize was given for Krugman's work explaining the patterns of international trade and the geographic concentration of wealth, by examining the impact of economies of scale and of consumer preferences for diverse goods and services.

Krugman is known in academia for his work on international economics (including trade theory, economic geography, and international finance),liquidity traps and currency crises. He is the 17th most widely cited economist in the world today and is ranked among the most influential academic thinkers in the US.