Open economy multiplier

Topic: Aggregate Demand, Income Determination and the Multiplier · NCERT: Class 12, Ch 6 "Open Economy Macroeconomics"

Meaning

The open economy multiplier tells us how much the equilibrium national income (the level of income at which total planned spending equals output) of a country that trades with the world rises when autonomous spending rises by one rupee. Autonomous spending means spending that does not depend on income, such as investment, government spending or exports.

k = ΔY/ΔĀ = 1/(1 − c + m), where c = marginal propensity to consume and m = marginal propensity to import.

It matters because it shows that imports are a leakage. When part of each extra rupee buys foreign goods, a stimulus raises home income much less than the closed-economy formula 1/(1 − c) predicts.

Explanation

Basic terms

• Marginal propensity to consume (MPC, c): the share of each extra rupee of income that people spend. c = ΔC/ΔY.
• Marginal propensity to import (m): the share of each extra rupee of income that people spend on foreign goods.
• Imports are one part of total spending. So m is part of c.

• The share spent on domestic goods is therefore (c − m).

• Leakage: any part of extra income that does not come back as demand for goods made at home. Saving, imports and taxes are the three main leakages.

• Injection: spending that enters the income stream from outside the household. Investment, government spending and exports are injections.

How it works, round by round

• Round 1: spending becomes income.
• Autonomous spending rises, for example through extra investment or extra exports.

• Firms produce more, and they pay the extra amount out as wages, rent, interest and profit.

• Round 2: income is split three ways.

• Some of it is saved. This is a leakage.
• Some of it buys imports. This spending raises output in the foreign country, not at home. It is a leakage.

• Only the rest, (c − m), becomes demand for domestic output and new domestic income.

• The chain shrinks faster than in a closed economy.

• Each round loses both saving and imports.
• So the rounds add up to a smaller total. The geometric series 1 + (c − m) + (c − m)² + … sums to 1/(1 − c + m).

Worked example (NCERT numbers)

• Closed economy: c = 0.8 → k = 1/(1 − 0.8) = 1/0.2 = 5.
• Open economy: c = 0.8, m = 0.3 → k = 1/(1 − 0.8 + 0.3) = 1/0.5 = 2.
• Effect of a rise in investment of 10:
• Closed economy: ΔY = 5 × 10 = 50.

• Open economy: ΔY = 2 × 10 = 20.

• Round by round in the open economy:

• Round 1: income rises by 10.
• Round 2: people spend 0.8 × 10 = 8. Of this, 3 goes on imports, so domestic demand rises by only 5.
• Round 3: domestic demand rises by 0.5 × 5 = 2.5, and so on.
• Total: 10 + 5 + 2.5 + … = 20.

What makes it rise or fall

• Higher c → larger multiplier. More of each round is spent.
• Higher m → smaller multiplier. More of each round leaks abroad.
• Higher saving (MPS = 1 − c) → smaller multiplier.
• Taxes are one more leakage. In the closed model, a proportional tax (a fixed share t of each extra rupee taken as tax) gives k = 1/(1 − c(1 − t)). With c = 0.8 and t = 0.25, k is 2.5 instead of 5. Taxes cut the open-economy multiplier in the same way.
• The multiplier works in both directions.
• A rise in exports is an injection, so it raises home income by k times.
• A fall in investment or exports lowers income by k times. This is how a slump spreads.

In India

• Import-heavy spending weakens the domestic multiplier.
• When a large share of extra spending goes on imported goods such as electronics and energy, m is high.
• Each round of stimulus then creates jobs and income abroad instead of at home.

• Schemes such as Make in India and PLI (Production Linked Incentive, which pays firms extra for making more in India) try to keep more of each round at home. In effect, they try to lower m.

• What kind of spending the government chooses matters.

• An RBI study found that capital outlay (spending that creates assets, such as roads and power plants) raises growth more than revenue expenditure (day-to-day spending such as salaries, interest and subsidies). The first-year multiplier of total government spending is less than one (RBI Bulletin, June 2021) [2].

• Studies cited by the government estimate that public spending on infrastructure raises GDP by about 2.5 to 3.5 times the amount spent over the medium term (Union Budget 2024-25) [4].

• Policy response:

• The Centre's capital outlay rose by about 89%, from ₹5.92 lakh crore (FY22) to ₹11.21 lakh crore budgeted for FY26. The stated reason is the strong multiplier effect of infrastructure (Economic Survey 2025-26) [3].

• States get 50-year interest-free loans for capital spending under the Special Assistance to States for Capital Investment, because of its higher multiplier and its role in crowding in private investment [3]. Crowding in means that public spending draws in more private investment.

• V.K.R.V. Rao (1952) caveat:

• In a poor economy, supply bottlenecks, a large non-monetised sector (output that people produce for their own use instead of selling) and farm output that cannot rise quickly all make the real multiplier weak.
• Extra demand then pushes up prices, not output.
• Where home supply cannot rise quickly, extra demand can also spill into imports.

Don't confuse with

• Closed-economy multiplier, 1/(1 − c) = 1/MPS: the only leakage in it is saving, and its value always lies between 1 and ∞. The open economy multiplier also counts imports, so it is smaller for the same c (2 instead of 5 in the NCERT example).
• Marginal propensity to import (m) vs import share of GDP: m is the share of each extra rupee spent on imports (ΔM/ΔY). The formula uses m, not the average share of imports in total income.
• Multiplier with proportional taxes, 1/(1 − c(1 − t)): here the leakage is tax, not imports. Both formulas make k smaller, but through different leakages.
• Injection vs leakage: exports are an injection that raises income through the multiplier. Imports are a leakage that reduces the multiplier's size. Do not mix them up in "which of the following" questions.

Prelims Hooks

• Open economy multiplier = 1/(1 − c + m). With c = 0.8 and m = 0.3, k = 2, compared with 5 in a closed economy (NCERT Class 12, Open Economy Macroeconomics).
• A higher marginal propensity to import → a smaller multiplier. Trap: "opening up to trade raises the multiplier" is wrong.
• Saving, taxes and imports are leakages. Investment, government spending and exports are injections.
• A rise in exports raises equilibrium income by k times the rise, just like a rise in investment.
• The rule that "k lies between 1 and ∞" holds for the simple closed-economy model (k = 1/MPS). With trade, k is smaller, but it stays above 1 as long as m is less than c.
• RBI (June 2021): capital outlay has higher growth multipliers than revenue expenditure. The first-year multiplier of total government spending is below 1 [2].

Mains Points

• Import leakage and domestic capacity (GS-III, industrial policy):
• A high marginal propensity to import (for example, electronics and energy) cuts the multiplier sharply: from 5 to 2 in the NCERT example.
• This is a macro argument for building capacity at home through Make in India and PLI, so that more of each spending round creates income in India.

• Trade-off: import substitution that goes too far can raise costs and hurt competitiveness.

• Quality of public spending (GS-III, fiscal policy):

• Revenue spending has low, short-lived multipliers. Capital outlay has higher ones, about 2.5–3.5 over the medium term by government-cited estimates [2][4].
• This supports the rise in capex from ₹5.92 lakh crore (FY22) to ₹11.21 lakh crore (FY26 BE) [3].

• The multiplier is larger when capex uses domestic inputs, such as Indian steel and cement, rather than imported ones.

• Stimulus in an open, developing economy:

• Rao's 1952 critique still applies. When home supply is short, extra demand turns into higher prices and more imports, and output rises little.
• So demand stimulus needs supply-side reforms alongside it, such as infrastructure, farm productivity and formalisation.
• It also needs attention to the current account deficit (the gap when a country's payments to the world are larger than its receipts), because more imports widen it.

Related concepts

• Investment multiplier
• Multiplier mechanism
• Parametric shift

Read more

• The investment multiplier and its round-by-round mechanism