National Income Accounting

Written and reviewed by Devendra Dubey, Mathematics & Commerce faculty at UniDrill (M.Sc. Mathematics, Osmania University · 10 years teaching). Based on NCERT Economics Class XII (Introductory Macroeconomics), Chapter 2.

How do you count a country's output without counting anything twice?

A farmer grows cotton. A mill spins it into yarn. A textile mill weaves the yarn into cloth. A tailor makes a shirt from the cloth, and you buy the shirt. If you add the value of the cotton, the yarn, the cloth and the shirt, you have counted the same cotton four times. This chapter is about avoiding that error and turning a country's whole production into one number.

You will meet that number in many forms: GDP, GNP, NNP, national income, personal disposable income. They look like alphabet soup, but each is one adjustment away from the next. Learn the logic of the ladder, and the formulas stop being things to memorise.

Building blocks: what is being counted

The wealth of a country does not depend on the mere possession of resources. Several resource rich regions are among the poorest, while many prosperous countries have little natural wealth. What matters is how resources are turned into a flow of production and how that flow generates income.

Final and intermediate goods. A final good is meant for final use and will not pass through any more stages of production. An intermediate good is used up as an input to make another good, like steel sheets for cars or copper for utensils. The same item can be either, depending on use. Tea leaves bought by a household are final; the same tea leaves bought by a restaurant are an input, because the restaurant adds value and sells the tea. As the book puts it, it is the economic nature of the use, not the nature of the good, that decides.

Why only final goods are counted. The price of a final good already contains the value of every intermediate good that went into it. Counting both is double counting, and it would hugely exaggerate output.

Stocks and flows. A flow is measured over a period of time (income, output, profit, investment, value added). A stock is measured at a point in time (the number of machines in a factory, the capital stock, inventories). Think of a tap filling a tank: the water coming in per minute is a flow, the water in the tank right now is a stock. The change in a stock over a period is a flow: machines added this year are a flow even though the machines themselves are part of the stock.

Investment and depreciation. The part of final output made up of capital goods is gross investment. Some of it only replaces capital that wore out, and that part is depreciation, so:

$$\text{Net investment} = \text{Gross investment} - \text{Depreciation}$$

Net investment is the true addition to the capital stock. Depreciation is the annual allowance for wear and tear. For a machine, it is the cost divided by the years of useful life, so a ₹10,00,000 machine with a 20 year life has an annual depreciation of ₹50,000. It is an accounting idea: no cash need be spent in that particular year, though across thousands of firms the actual replacement spending roughly matches the depreciation recorded.

An economist's investment is capital formation. Buying shares, property or an insurance policy is not investment in this sense.

The trade-off over time. In any one year, producing more capital goods means fewer consumer goods. But more capital goods today make labour more productive, so total output (and consumer goods) can be higher in the future. There is no contradiction once you add the element of time.

The circular flow: why spending, output and income are the same number

Take a simple economy with only households and firms, with no savings, no government and no foreign trade. Firms hire factors of production and pay them for four contributions: labour earns wages, capital earns interest, entrepreneurship earns profit and land earns rent. Households spend all of this income on what the firms produced. So every rupee that firms pay out comes straight back as sales revenue.

That gives three places to measure the same flow:

Why the three must match. Whatever is produced is sold. Whatever is sold is someone's spending. Whatever firms receive as revenue is paid out to factors, and what is left over is profit. The model leaves out savings, government and trade, but the conclusion survives when they are added back: however complicated the economy, the three methods give the same figure.

A note on aggregates versus individuals. If households decide to spend more, firms will produce more to meet it, paying out more to factors. Household income rises by about what the extra spending needs. This looks paradoxical, but it is the circular flow at work. A single worker cannot spend more and thereby raise her own income, but an economy can. This is a feature of the aggregate that does not carry over to one agent, and it leads straight to the multiplier in Chapter 4.

Method 1: Product or value added

Value added is a firm's net contribution: the value of its production minus the intermediate goods it used. It is a flow variable, and it is exactly what the firm distributes to its factors as wages, interest, profit and rent.

The book's example has two producers. Farmers grow wheat worth ₹100 using no inputs and sell ₹50 of it to bakers. Bakers produce bread worth ₹200.

Adding the outputs gives ₹300, which counts the ₹50 of wheat twice. Adding value added gives ₹250, the correct figure.

Gross and net value added. Adding depreciation back into value added gives gross value added (GVA). Taking it out gives net value added (NVA). If a firm produces ₹100 of goods, uses ₹20 of intermediate goods and has ₹10 of depreciation, GVA is ₹80 and NVA is ₹70.

Inventories. A firm may not sell all it produces. Inventory is the stock of unsold finished goods, semi-finished goods or raw materials. Its change during the year is a flow:

$$\text{Change in inventories} \equiv \text{Production} - \text{Sales}$$

The sign $\equiv$ marks an identity, true for every value of the variables, unlike an equation, which holds only for particular values. Because inventories are treated as capital, a rise in inventories counts as investment. There are three kinds of investment: the change in inventories, fixed business investment (machinery, factory buildings, equipment) and residential investment (housing).

Change in inventories can be planned or unplanned. Suppose a firm starts with 100 shirts and expects to sell 1,000, so it makes 1,000 shirts. If only 600 sell, the firm ends the year with 500 shirts. The extra 400 is an unplanned accumulation. If 1,050 sell, 50 shirts come out of stock, an unplanned decumulation. If instead the firm wanted to raise stock from 100 to 200, it would make 1,100 shirts, and ending with 200 is a planned change.

Pause and predict: a firm starts with a stock of 100 shirts, expects to sell 1,000 and makes 1,000. Sales turn out to be 1,000. Is there any change in inventories?

Check your answer: no. Production equals sales, so the stock stays at 100. The change is zero, whether we call it planned or unplanned.

Putting inventories into value added gives, for a firm $i$:

$$GVA_i \equiv V_i + \Delta A_i - Z_i$$

where $V_i$ is sales, $\Delta A_i$ is the change in inventories and $Z_i$ is the intermediate goods used. Sales include sales abroad (exports). GDP is the sum of gross value added of all firms, $GDP \equiv \sum_{i=1}^{N} GVA_i$.

Method 2: Expenditure

Instead of counting output, count what is spent on it. Only final expenditure counts, because spending on intermediate goods is already inside the price of final goods. The final expenditure received by firms comes from four sources: consumption ($C$), investment ($I$), government spending ($G$) and exports ($X$). Some of each of the first three is spent on imported goods, which are not produced by domestic firms. Subtract total imports $M$ and you get:

$$GDP \equiv C + I + G + X - M$$

Why imports are subtracted. $C$, $I$ and $G$ measure all spending by residents, including on foreign goods. Income earned by domestic firms comes only from domestic output, so the spending that went abroad must be taken out. Exports are added because foreigners spend on our output. Investment here is both planned and unplanned, including the change in inventories. Of the five terms, investment is the most unstable.

Method 3: Income

Add up what factors receive: wages and salaries $W$, gross profits $P$, interest $In$ and rent $R$.

$$GDP \equiv W + P + In + R$$

The three methods in one line:

$$GDP \equiv \sum_{i=1}^{N} GVA_i \equiv C + I + G + X - M \equiv W + P + In + R$$

The book's check: firm A produces cotton worth ₹50 with no inputs and sells it to firm B, which makes cloth and sells it to consumers for ₹200. Value added is $50 + (200 - 50) = 200$. Final expenditure is the consumers' ₹200 on cloth. Income: if A pays ₹20 as wages and keeps ₹30 as profit, and B pays ₹60 as wages and keeps ₹90, total wages and profits are $80 + 120 = 200$. All three methods give ₹200.

Factor cost, basic prices and market prices

The price a consumer pays includes taxes on the product, while the firm and its factors receive less. To compare, you must say which price is used.

Each "net" means taxes less subsidies. Together, net product taxes plus net production taxes make net indirect taxes (NIT), which is indirect taxes less subsidies.

$$\text{GVA}{FC} + \text{Net production taxes} = \text{GVA}{BP}, \qquad \text{GVA}{BP} + \text{Net product taxes} = \text{GVA}{MP}$$

India's statistical office changed its headline measure in 2015: GDP at market prices, now called simply GDP, and GVA at basic prices became the most highlighted measures, in place of GDP at factor cost.

The ladder of aggregates

GDP counts production inside the country's borders, whoever owns the factors. GNP counts production by the country's normal residents, wherever it happens. An Indian working in Saudi Arabia adds to Saudi GDP, but her earnings belong to India's GNP. The profits of a Korean owned car factory in India are in India's GDP, but not in India's GNP. The adjustment is net factor income from abroad (NFIA):

$$NFIA = \text{Factor income earned by residents abroad} - \text{Factor income earned by foreigners at home}$$

Then each step down removes something specific.

Why national income is NNP at factor cost. It is the amount that actually accrues to the country's factors of production. So you deduct depreciation (it is not income to anyone), and you deduct net indirect taxes (they go to the government) to get from market prices to factor cost.

From national income to what households keep. National income is earned by firms, government enterprises and households. Part of it never reaches households, and households also receive some money that is not earned income.

Two more categories appear in India's accounts. National Disposable Income is NNP at market prices plus other current transfers from the rest of the world (gifts and aids), and shows the most goods and services the economy has at its disposal. Private Income adds up factor income from net domestic product accruing to the private sector, interest on national debt, NFIA, current transfers from the government and other net transfers from abroad.

Beyond the textbook. For the exam: GDP is the value of final goods and services produced in the year, and we add up value added. In reality: national accountants also leave out second hand sales (only the dealer's margin is new production), purchases of shares and bonds, and transfers such as pensions, because none of these is current production. Why it matters: a question that asks whether a given transaction enters GDP is really asking whether new goods or services were produced in the year.

Nominal and real GDP, and price indices

If prices change, comparing GDP across years is misleading. A GDP that doubles might simply reflect prices doubling with unchanged output. Nominal GDP is the value at current prices. Real GDP values output at the prices of a fixed base year, so any change in it reflects only a change in the volume of production. The ratio of nominal to real GDP shows how much prices have moved, and it is the GDP deflator:

$$\text{GDP deflator} = \dfrac{\text{Nominal GDP}}{\text{Real GDP}} \times 100$$

The Consumer Price Index (CPI) is the cost of a fixed basket bought by a representative consumer in the current year, as a percentage of its cost in the base year. The Wholesale Price Index (WPI) is the same idea for goods traded in bulk (in the USA it is called the Producer Price Index).

Beyond the textbook. For the exam: three price indices, GDP deflator, CPI and WPI, each measure how prices change. In reality: the CPI is the index most closely tied to households' cost of living, and in India the RBI's inflation target is stated in terms of consumer price inflation. Why it matters: when you read "inflation" in the news, it usually means the change in a consumer price index, not in the GDP deflator.

Worked examples

Worked example: value added along a chain. A farmer grows wheat worth ₹400 with no purchased inputs and sells it all to a miller. The miller sells flour worth ₹700 to a baker. The baker sells bread worth ₹1,000 to consumers. Find the GDP created by this chain.

Common wrong step. Adding the outputs: 400 + 700 + 1,000 = ₹2,100. The wheat is counted three times and the flour twice. The sum of value added always equals the price of the final good.

Worked example: inventories and value added. A firm began the year with a stock of ₹100. It produced goods worth ₹1,000, sold ₹800, used ₹300 of intermediate goods and had depreciation of ₹50. Find its gross and net value added.

Common wrong step. Ignoring inventories and writing 800 − 300 = ₹500. The unsold ₹200 was still produced and is counted as investment in stock, so leaving it out understates value added.

Worked example: from expenditure to national income. In a year (₹ crore): $C = 900$, $I = 350$ (including change in stocks), $G = 250$, $X = 150$, $M = 200$. Net factor income from abroad is −50, depreciation is 130, net product taxes are 110 and net production taxes are 60. Find GDP at market prices, GNP at market prices, NNP at market prices, GDP at factor cost and national income.

Common wrong step. Subtracting NFIA instead of adding it in Step 2, which gives 1,500. NFIA is added whether positive or negative; here it is negative, which lowers GNP below GDP. A second slip is deducting only the net product taxes (110) in Step 6, which gives 1,160. Going to factor cost removes both kinds of net indirect taxes.

Worked example: personal income and disposable income. With national income of ₹1,100 crore, undistributed profits are ₹90 crore, corporate tax ₹50 crore, net interest paid by households ₹10 crore and transfers to households ₹70 crore. Personal tax is ₹110 crore and non-tax payments are ₹10 crore.

Common wrong step. Subtracting the transfer payments (which gives 880) instead of adding them. Transfers are income that households receive without producing anything, so they raise personal income even though they are not part of national income. Another slip is to stop at ₹910 crore by forgetting the non-tax payments.

Worked example: nominal GDP, real GDP and the deflator. An economy produces only bread. In the base year it makes 200 units at ₹20 each. In the current year it makes 220 units at ₹28 each. Find nominal GDP, real GDP, the deflator and the growth rates.

Common wrong step. Saying output grew 54%. Most of that is price rise: 1.10 × 1.40 = 1.54. Real GDP is the quantity measure, and it grew by 10%.

Worked example: the consumer price index. A consumer buys 80 kg of rice and 6 pieces of cloth a year. In the base year, rice costs ₹20 per kg and cloth ₹150 per piece. In the current year, the prices are ₹25 and ₹180.

Common wrong step. Averaging the two price rises: rice up 25%, cloth up 20%, mean 22.5%, so index 122.5. The basket weights matter: rice takes a larger share of the spending, so the index leans towards the rice price rise.

Pause and predict: prices double and output stays the same. What happens to nominal GDP, real GDP and the deflator?

Check your answer: nominal GDP doubles, real GDP is unchanged, and the deflator rises from 100 to 200. That is why real GDP, not nominal GDP, is used to compare output over time.

GDP and welfare: why a bigger number does not always mean better lives

It is tempting to treat GDP as an index of well-being, since higher incomes buy more. There are at least three reasons it may mislead.

Beyond the textbook. For the exam: GDP leaves out unpaid household work, which is why it may understate activity. In reality: many statistical offices run time use surveys to estimate how much unpaid household work is done, and they report it separately from GDP. Why it matters: it shows the omission is a deliberate accounting boundary, not an oversight, and it explains why GDP is described as a measure of market production, not of well-being.

Exam traps

Formula sheet

60-second revision

Where this chapter connects

These aggregates are the numbers that Introduction promised: the four sectors reappear as $C$, $I$, $G$ and $X - M$. The price level and the RBI's role come next in Money and Banking. The idea that spending determines output, hinted at in the circular flow, is developed in Determination of Income and Employment. Government spending and taxes are the subject of Government Budget and the Economy, and imports, exports and NFIA return in Open Economy Macroeconomics.