Why should income equal expenditure GDP?
Every dollar spent becomes someone's income. When you buy goods, that spending becomes wages, rent, interest, or profits for producers. It's two sides of the same transaction—the circular flow.
What's included in labor compensation?
Wages, salaries, bonuses, and employer contributions to benefits (health insurance, retirement). Includes both cash and non-cash compensation. Self-employed income is split between labor and capital.
Why is the labor share declining?
Multiple factors: automation, globalization, declining union power, winner-take-all dynamics in tech, and measurement issues with intangible capital. Economists debate relative importance.
What are indirect taxes?
Taxes on goods/services rather than income: sales tax, excise tax, property tax. They're part of GDP (price paid) but not factor income. Subsidies are the opposite—they're subtracted.
What is the difference between the income, expenditure, and production approaches?
All three measure the same thing — total output — from different angles. Income sums what producers pay out (W + R + i + Π plus depreciation and indirect taxes). Expenditure sums what buyers spend (C + I + G + NX). Production sums value added at each stage (output minus intermediate inputs). In an ideal accounting framework they're identical; in real data they differ slightly because they're built from independent surveys.
Why don't the three approaches always match in real data?
The BEA reports a 'statistical discrepancy' line — typically 0.5% to 2% of GDP — that captures the gap between Gross Domestic Product (expenditure side) and Gross Domestic Income (income side). The two are constructed from different source data: tax filings, business surveys, and household surveys each have measurement error. Researchers including Jeremy Nalewaik have argued that GDI is the more reliable measure at business-cycle turning points.
What is included in 'profits' in the income approach?
It includes corporate profits before tax (with the inventory valuation and capital consumption adjustments), plus proprietors' income — earnings of unincorporated businesses, partnerships, and self-employed professionals. The proprietor's-income line mixes labor and capital returns, which is one reason headline labor-share figures can vary by 5+ percentage points depending on how it is split.
How does the income approach differ from GNI?
GDP (any approach) measures output produced inside the country's borders. Gross National Income (GNI) measures income earned by the country's residents, regardless of where production occurs. GNI = GDP + net primary income from abroad. For the United States, the two differ by less than 1%; for small open economies with large foreign-owned sectors (Ireland, Luxembourg), the gap can exceed 15% of GDP.
Why include depreciation if it just replaces worn-out capital?
Because GDP is a gross measure — it counts all new capital goods produced this year, including those that merely replace existing equipment. Net Domestic Product (NDP = GDP − depreciation) is the 'net of replacement' measure economists use when they care about additions to the capital stock. Statistical agencies report GDP rather than NDP because depreciation is hard to measure accurately.
Does the calculator capture the underground economy?
Only to the extent that you enter values from official statistics that already include estimates of unreported activity. BEA and statistical agencies in most OECD countries impute amounts for the shadow economy — tip income, cash construction work, and so on — but coverage is incomplete. Most estimates put the US informal economy at 8–12% of GDP and Italy's or Greece's at 20–25%.
How do subsidies fit into 'indirect taxes'?
The proper line is 'taxes on production and imports less subsidies on production.' Subsidies are negative indirect taxes — they lower the market price below factor cost — so they reduce the bridge from National Income to GDP. In agricultural exporters and EU members where farm subsidies are substantial, net indirect taxes can be 1–2 percentage points lower than gross indirect taxes.
Can I use the calculator for historical data or other countries?
Yes. The formula is identical across the System of National Accounts (SNA 2008) used by every OECD member. Pull the six inputs from BEA NIPA Table 1.10 for the United States, Eurostat National Accounts for EU members, or OECD.Stat for cross-country comparisons. Always use the same source year and the same nominal-vs-real convention for every input.
