Cambridge A Level Economics: Effectiveness of fiscal and monetary policy including the Laffer curve (9708) – Revision Notes

These notes condense part of outcome 10.3.1 (fiscal policy including Laffer curve analysis, and monetary policy) and outcomes 10.3.2 and 10.3.3 of the Cambridge International AS & A Level Economics 9708 syllabus for examination in 2026, 2027 and 2028. Topics 1 to 6 are AS Level content and topics 7 to 11 are A Level content, so this unit is A Level only. Figures are invented and money is in zu.

Full explanations are in the study guide. Test yourself with the practice set, then check progress on the hub, the checklist and the free 10-minute diagnostics. For AS background, see the fiscal policy guide and the monetary policy guide.

Key definitions

Term	Meaning
Fiscal policy	Changes to government spending, taxation and the budget balance to influence the economy
Monetary policy	Central bank action on interest rates, money supply and related tools
Multiplier	The ratio of a change in output to the initial change in an injection
Crowding out	Public borrowing pushes up interest rates and reduces private investment
Laffer curve	The relationship between the tax rate and tax revenue, rising then falling
Quantitative easing	The central bank creates money and buys bonds to lower yields and raise spending
Real interest rate	The nominal interest rate minus the inflation rate
Government failure	Intervention that leaves the economy worse off than expected or worse than without it

Formulas and methods

Item	Method
Multiplier	k = 1 / (s + t + m), with s, t and m as marginal propensities to save, be taxed and import
Output change	k × change in the injection
Net injection with crowding out	Government spending change minus the fall in private investment
Tax revenue	Tax rate × tax base
Real interest rate	Nominal rate − inflation rate (approximate)
Bond yield	Annual payment / price paid
Debt ratio	National debt / nominal GDP × 100
Import change	Income elasticity of imports × percentage growth in income

Method in steps: a multiplier question

1. Add the three marginal propensities to get the withdrawal rate.
2. Take the reciprocal to get k.
3. Multiply by the injection.
4. Use t × change in output for extra tax revenue.
5. Subtract that revenue from the spending rise to find the change in the deficit.

Worked reminder 1

With s = 0.05, t = 0.20 and m = 0.15, withdrawals are 0.40 and k = 2.5. A spending rise of 16 raises output by 40. Tax revenue rises by 0.20 × 40 = 8, so the deficit rises by 16 − 8 = 8.

The Laffer curve

• Axes: tax rate (horizontal), tax revenue (vertical).
• Shape: revenue is zero at 0% and at 100%, with a maximum between.
• Left of the peak, a higher rate raises revenue. Right of the peak, a higher rate lowers it.
• Arithmetic effect: more revenue per unit of income. Behavioural effect: a smaller base through less work, avoidance, evasion and emigration.

Worked reminder 2

Base = 300 − 2t (zu bn), revenue = t × base / 100.

Rate (%)	Base	Revenue
50	200	100
60	180	108
75	150	112.5
80	140	112
90	120	108

The peak is at 75%. A cut from 90% to 80% raises revenue by 4, because the rate is beyond the peak. A cut from 60% to 50% loses 8.

Laffer evaluation points

• The peak is not observable, and it varies by tax and country.
• Revenue may not be the aim. Growth, incentives and equity can matter more.
• Behaviour takes time to change, so revenue may fall first.
• A cut beyond the peak is not the same as a cut that raises growth.

Fiscal policy: effectiveness by objective

Objective	Works through	Main limit
Growth	Spending and tax cuts raise AD	Short-run effect unless capacity grows
Unemployment	Higher AD cuts cyclical unemployment	No help for structural unemployment
Inflation	Cuts in AD reduce demand-pull inflation	Not cost-push, and politically hard
Balance of payments	Lower demand cuts imports	Expansion pulls in imports
Redistribution	Progressive tax and transfers	Possible effect on incentives
Sustainability	Taxes, subsidies, green spending	Tax base may fall as behaviour changes

Fiscal strengths: it can be targeted at groups or regions, automatic stabilisers work without delay, and spending on infrastructure can lift capacity.

Fiscal weaknesses: long lags, deficit and debt costs, crowding out, and political pressure.

Monetary policy: effectiveness by objective

Objective	Works through	Main limit
Inflation	Higher rates cut consumption and investment and raise the exchange rate	Weak against cost-push
Growth	Lower rates raise borrowing and spending	Weak when confidence is low
Unemployment	Higher AD cuts cyclical unemployment	Not structural
Balance of payments	Higher rates raise the exchange rate	Effects on the balance depend on elasticities
Redistribution	Not a tool for this	Savers and borrowers affected unevenly

Monetary strengths: quick to change, operated by a central bank at a distance from elections, and flexible in size.

Monetary weaknesses: lags before full effect, a blunt tool for the whole economy, little power when rates are near zero, and a limited effect on spending if banks do not lend.

Quantitative easing works by lowering bond yields. A bond paying 4 for a price of 80 yields 4/80 = 5%. At a price of 100 it yields 4%.

Worked reminder 3

A government spends 16 more, but borrowing pushes up rates and private investment falls by 4. The net injection is 16 − 4 = 12. With k = 2.5 the output rise is 30, not 40. Crowding out cut the effect by a quarter.

Evaluation checklist for any policy

1. Is there spare capacity? If so, expansion is less likely to raise prices.
2. What is the cause of the problem: demand, costs or structure?
3. How long is the lag, and could conditions change before it works?
4. Which other objective gets worse?
5. How uncertain is the size of the effect?
6. What does the final judgement depend on?

Problems and conflicts

Conflict	Reason
Inflation against unemployment	Lower AD cuts inflation but also output
Growth against balance of payments	Higher income draws in imports
Growth against sustainability	More output can mean more resource use
Redistribution against incentives	High taxes may reduce effort
Deficit reduction against recovery	Cuts lower AD in a slump
Tight money with loose fiscal policy	High rates, crowding out, a stronger currency
Time lags	Policy arrives after conditions change

Government failure

• Information: poor forecasts and uncertain output gaps.
• Time lags that make policy pro-cyclical.
• Political motives such as pre-election giveaways.
• Conflicting objectives.
• Unintended consequences such as evasion at high rates.
• Crowding out of private investment.
• A central bank pressed to finance government borrowing.

Must-know distinctions

• Cyclical unemployment responds to AD policy. Structural unemployment does not.
• Demand-pull inflation responds to tighter demand. Cost-push inflation needs a supply response.
• Nominal rate against real rate.
• Arithmetic effect against behavioural effect on the Laffer curve.
• A discretionary change against an automatic stabiliser.

Quick self-test

1. Define the Laffer curve.
2. With s = 0.08, t = 0.22 and m = 0.30, what is the multiplier, to 2 decimal places?
3. A spending rise of 16 with k = 2.5 raises output by how much?
4. Using the table above, how does revenue change if the rate falls from 90% to 80%?
5. What is the real interest rate if the nominal rate is 3% and inflation is 5%?
6. A bond with a payment of 4 costs 80. What is its yield?
7. National debt is 300 and nominal GDP is 400. What is the debt ratio?
8. Why is monetary policy weak against cost-push inflation?
9. Name two policy conflicts.
10. Give two examples of government failure.

Answers

1. It shows tax revenue against the tax rate. Revenue rises, reaches a maximum, then falls as higher rates shrink the tax base.
2. The withdrawals are 0.08 + 0.22 + 0.30 = 0.60, so k = 1 / 0.60 = 1.67.
3. 2.5 × 16 = 40.
4. Revenue rises from 108 to 112, a rise of 4.
5. 3 − 5 = −2%.
6. 4 / 80 = 5%.
7. 300 / 400 = 75%.
8. Higher rates cut demand, but cost-push inflation comes from rising costs. Cutting demand lowers output and employment without removing the cost pressure.
9. Any two from: inflation against unemployment, growth against the balance of payments, growth against sustainability, redistribution against incentives.
10. Any two from: poor information, time lags, political motives, crowding out, unintended consequences.

Where marks are usually lost

• Giving a Laffer curve peak as a fact instead of an assumption.
• Forgetting that taxes and imports reduce the multiplier.
• Applying monetary policy to cost-push inflation without saying it is weak.
• Mixing up nominal and real interest rates.
• Describing a diagram with unlabelled axes or without naming the equilibrium.
• Listing evaluation points without a conclusion that says what it depends on.
• Writing about all policies when the question names one.
• Ignoring that a conflict has two sides, so only one objective is explained.

Official syllabus

Cambridge International AS & A Level Economics 9708 syllabus, for examination in 2026, 2027 and 2028, version 2, published by Cambridge University Press & Assessment. These notes cover part of outcome 10.3.1 and outcomes 10.3.2 and 10.3.3.