Excess Demand and Deficient Demand
Inflationary and deflationary gaps, and the fiscal and monetary measures used to correct them.
Definition
Excess demand exists when Aggregate Demand exceeds the Aggregate Supply corresponding to full-employment output; deficient demand exists when Aggregate Demand falls short of the Aggregate Supply needed to sustain full employment.
Simple Explanation
These describe the two ways an economy's total spending can go 'wrong' relative to what it can actually produce at full employment — spending too much, or too little.
Detailed Explanation
An inflationary gap arises under excess demand: since output cannot rise any further once the economy is already at full employment, the excess spending only pulls up the general price level instead of raising real output — this is demand-pull inflation. A deflationary gap arises under deficient demand: equilibrium income settles below the full-employment level, leaving part of the labour force involuntarily unemployed, since AD is not strong enough to absorb all the output the economy is capable of producing at full employment.
The size of either gap is measured as the vertical distance between the actual AD curve and the AD curve that would be needed to achieve exactly full-employment equilibrium — this distance is what fiscal and monetary policy aim to close.
To correct deficient demand (a deflationary gap), the government uses expansionary fiscal policy — raising its own spending and/or cutting taxes, both of which directly raise AD — alongside expansionary monetary policy from the central bank, which cuts the repo rate, Cash Reserve Ratio, and Statutory Liquidity Ratio to make credit cheaper and more freely available, encouraging private investment and consumption.
To correct excess demand (an inflationary gap), the same tools work in reverse: contractionary fiscal policy — cutting government spending and/or raising taxes — withdraws spending power directly, while contractionary monetary policy raises the repo rate, CRR, and SLR to make credit costlier and scarcer, cooling down both investment and consumption.
Because of the multiplier studied in the previous chapter, policymakers do not need to close an entire gap through new spending alone — a comparatively modest, well-targeted fiscal injection, magnified by the multiplier, can close a much larger deflationary gap, which is exactly why governments favour multiplier-amplified spending over equally-sized direct transfers during a slowdown.
Real-life Examples
Deflationary gap response
During an economic slowdown, a government cutting income tax rates puts more disposable income in households' hands, raising consumption (C) and helping close a deflationary gap.
Inflationary gap response
When prices are rising too fast because demand has overheated, the RBI raising the repo rate makes loans costlier, cooling down both consumer spending and business investment.
Step-by-step Graph
- 1
Draw the full-employment line
Mark a vertical line at the full-employment level of income (YF) on the AD-AS diagram.
- 2
Plot the actual AD curve
Draw the actual AD curve intersecting the 45° line either before YF (deflationary gap) or beyond what YF can supply (inflationary gap).
- 3
Mark the gap
Draw a second, dashed AD curve that would pass exactly through the full-employment equilibrium point, and mark the vertical distance between the two AD curves as the gap.
- 4
Label the direction of correction
For a deflationary gap, show AD needing to shift up to close it; for an inflationary gap, show AD needing to shift down.
Tables
| Gap | Fiscal policy response | Monetary policy response |
|---|---|---|
| Deflationary gap (deficient demand) | Raise government spending; cut taxes | Cut repo rate, CRR, SLR |
| Inflationary gap (excess demand) | Cut government spending; raise taxes | Raise repo rate, CRR, SLR |
Common Mistakes
- Believing an inflationary gap means output keeps rising — at full employment, output is already maxed out, so excess demand raises prices instead.
- Mixing up the direction of fiscal correction — deficient demand needs MORE government spending/LESS tax, not the reverse.
- Forgetting that monetary tools (repo rate, CRR, SLR) move in the same direction as each other to correct a given gap.
Board Exam Tips
- Always state whether a measure is fiscal or monetary explicitly, and name the specific tool (e.g. 'cut in CRR', not just 'monetary policy').
- For gap-correction questions, organise your answer into two clear halves: fiscal measures, then monetary measures.
- Link your answer back to the multiplier where relevant — examiners reward noting that fiscal measures are amplified by the multiplier.
Summary
- Excess demand at full employment causes an inflationary gap, pulling up prices instead of output.
- Deficient demand causes a deflationary gap, leaving the economy below full employment.
- Deflationary gaps are corrected with expansionary fiscal and monetary policy.
- Inflationary gaps are corrected with contractionary fiscal and monetary policy.
- The multiplier means fiscal measures can close a gap without matching its full size in new spending.
Practice MCQs
1. A 'deflationary gap' refers to a situation where:
2. An 'inflationary gap' arises when:
3. To correct a deflationary gap, the central bank would typically:
4. An appropriate fiscal measure to correct an inflationary gap is to:
5. Why can fiscal policy close a deflationary gap without spending an amount equal to the entire gap?
6. At full employment, excess demand causes:
Previous Year Questions
What is meant by a deflationary gap? How can it be corrected through fiscal policy?
Why can equilibrium income be below the full-employment level of income? Explain.
Explain excess demand and deficient demand, and the fiscal policy measures used to correct each.