Question

Difficulty: MediumFiscal Policy Tools and Economic Stabilization

In an economy, the consumption function is given as C=50 billion+0.8YdC = ₦50\text{ billion} + 0.8 Y_d, where YdY_d represents disposable income. The government levies a flat proportional income tax rate of 25%25\% (t=0.25t = 0.25) on total national income (YY). If the economy is currently experiencing a recessionary output gap of 200 billion₦200\text{ billion}, calculate the required increase in government expenditure (ΔG\Delta G), in billions of Naira, to achieve full-employment equilibrium.

Answer: 80 billion Naira

Answer

The required increase in government expenditure is 80 billion Naira.
With a marginal propensity to consume of 0.80.8 and a proportional tax rate of 0.250.25, the effective consumption propensity relative to total income is 0.8×(10.25)=0.60.8 \times (1 - 0.25) = 0.6. The spending multiplier is Kg=110.6=2.5K_g = \frac{1}{1 - 0.6} = 2.5. Closing a 200 billion₦200\text{ billion} recessionary gap requires an initial government spending increase of 200 billion2.5=80 billion\frac{₦200\text{ billion}}{2.5} = ₦80\text{ billion}.

Step-by-Step Solution

1
Determine the effective marginal propensity to consume out of total income (MPCYMPC_Y)
MPCY=0.8×(10.25)=0.6MPC_Y = 0.8 \times (1 - 0.25) = 0.6
Taxation reduces disposable income, so out of every additional unit of national income, only (1t)(1 - t) remains available for consumption.
2
Calculate the fiscal spending multiplier (KgK_g)
Kg=110.6=2.5K_g = \frac{1}{1 - 0.6} = 2.5
The expenditure multiplier accounts for the automatic leakage caused by proportional income taxes.
3
Calculate the necessary government spending injection (ΔG\Delta G)
ΔG=2002.5=80 billion Naira\Delta G = \frac{200}{2.5} = 80\text{ billion Naira}
Dividing the target increase in national output by the multiplier yields the required initial discretionary fiscal boost.

Key Concept

Fiscal policy expenditure multiplier with proportional taxation
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