IB Economics Fiscal Policy Expansionary & Contractionary

Expansionary & Contractionary Fiscal Policy: How Governments Try to Fix (and Sometimes Break) the Economy

Target Question:

What is the difference between expansionary and contractionary fiscal policy in IB Economics?

In March 2020 the world completely came to a halt. Restaurants, cinemas, gyms - all remained closed. Millions of people stayed at home, most of them not working, not spending, not contributing to the economy in the way they would normally do. GDP fell by the minute. Unemployment turned from being a problem to being the only solution a lot of companies had to survive, many deciding to let all their workers go since there was no consumption and could not afford wages and salaries.

So what dis the government do when the economy stopped working? It opened its wallet. Massively.

In the UK, the Treasury launched the Furlough Scheme - officially the Coronavirus Job Retention Scheme - paying up to 80% of workers' wages. In the US, the government fired off $1,200 stimulus cheques directly into people's bank accounts. In the EU, member states collectively spent hundreds of billions supporting businesses and workers. Governments across the globe essentially said: "If the private sector won't spend, we will have to do it."

That is the best recent example of fiscal policy you can find and a great introduction to today's entry.

What Is Fiscal Policy?

Fiscal policy refers to a government's use of government spending (G) and taxation (T) to influence the level of economic activity. In simple terms, this is like the economy's volume dial - the government can turn it up when things are too quiet, or turn it down when things are getting too loud. So the government through fiscal policy can encourage a slow economy or discourage an economy that is growing too quickly.

Government spending (G) as a quick reminder for my students is part of the formula for Aggregate Demand:

AD = C + I + G + (X − M)

Where:

• C = Consumer spending

• I = Investment (firms)

• G = Government expenditure

• X − M = Net exports

So when a government increases spending, it directly shifts the AD curve to the right. Instantly. No delay. That's what makes G such a powerful instrument compared to, say, trying to regain the confidence of consumers or businesses and convince them to spend more - the government can stimulate the economy quickly and efficiently.

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Expansionary Fiscal Policy

Expansionary fiscal policy is used when the economy is in a slump - unemployment is rising, growth is weak, and the country is operating below its potential. The aim is to stimulate demand by:

• Increasing government spending (G) - on infrastructure, public services, welfare benefits, etc.

• Cutting taxes - giving households more disposable income (boosting C) and giving businesses more incentive to invest (boosting I)

So, expansionary fiscal policy is a demand-side policy in which a government increases spending and/or cuts taxes to stimulate aggregate demand, aiming to close a deflationary gap and reduce unemployment.

The goal is to close what economists call a deflationary (or recessionary) gap - the gap between where the economy currently is and where it should be at full employment.

The Keynesian Case for Spending

Keynesian economists - the intellectual followers of John Maynard Keynes, the economist who supported "just spend your way out of it" - believe governments should intervene during downturns. They argue the private sector won't always save itself, so the government has to step in.

On the Keynesian AS diagram, here's how expansionary fiscal policy plays out:

• A first injection of spending shifts AD from AD₁ → AD₂, increasing real GDP from Y₀ → Y₁, while the price level stays flat at PL₁ (there's spare capacity in the economy, so no inflationary pressure yet - it's a flat AS curve in that range).

• If spending continues, AD shifts from AD₂ → AD₃, pushing real GDP to Y₂. Now we're getting closer to full capacity, and the price level starts rising from PL₁ → PL₂ - some inflationary pressure kicks in.

• Push it even further - AD₃ → AD₄ - and you're getting into the steep part of the AS curve. Real GDP barely changes (Y₂ → YF), but the price level jumps sharply (PL₂ → PL₃). Why? Because the factors of production (land, labour, capital) are becoming increasingly scarce. You can't produce much more, so the extra demand just inflates prices.

Keynesians agree with using expansionary policy to close the gap and reach YF (full employment output) - but they would also tell you not to push past it.

IB Economics Real-Life Example: Rachel Reeves and the UK's 2025 Budget

In November 2025, UK Chancellor Rachel Reeves delivered the second Labour Budget in two years - and it was a typical example of fiscal balancing act. Tax policy decisions were forecast to raise £26.6 billion by 2030/31, increasing the tax take to 38% of GDP. At the same time, the big winners of the Spending Review were the NHS and defence - with NHS budgets rising by 3% a year in real terms, and defence spending set to rise to 2.5% of GDP by 2027–28.

In 2025–26, UK public spending is expected to reach £1,370 billion - equivalent to roughly £48,000 per household, or 45% of national income. That's a huge number. And it illustrates just how decisive government expenditure is to the UK's aggregate demand.

Contractionary Fiscal Policy

Imagine the economy is overheating - economic growth is too fast, inflation is rising uncomfortably, and the central bank is getting nervous. Think of the post-COVID boom period when supply chains were hardly working properly and too much money was chasing too few goods.

Contractionary fiscal policy does the opposite - it aims to reduce aggregate demand by:

• Cutting government spending - reducing G directly

• Raising taxes - reducing disposable income (C falls) and making investment less attractive (I falls)

The goal here is to close an inflationary gap - pulling the economy back from an unsustainable boom.

So, contractionary fiscal policy involves cutting government spending and/or raising taxes to reduce aggregate demand, used to control inflation during an economic boom by closing an inflationary gap.

From the monetarist/new classical perspective, this is a situation they feel comfortable with. Monetarists are pretty sceptical of the whole "government spending will save us" story. Their argument? Demand-side policies like expansionary fiscal policy don't actually increase real GDP in the long run - they just push up the price level.

The UK's 2025 Budget is projected to reduce CPI inflation by 0.4 percentage points in 2026–27 - and the government explicitly explained that its fiscal tightening was being implemented in order to support the Bank of England's effort to bring inflation sustainably back to target.

Monetarists would rather use supply-side policies to grow the economy's productive capacity (the LRAS curve) instead of encouraging demand directly. In their view, if you want to reduce the natural rate of unemployment long-term, train workers, deregulate markets, and improve incentives - there is no need to just throw money at the problem.

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The Keynesian Multiplier (HL)

When a government injects money into the economy, the impact doesn't stop at that initial injection. The money gets recycled through the economy, creating a chain reaction of spending. This is the Keynesian multiplier.

The Keynesian multiplier measures the proportionate increase in aggregate demand that results from an initial injection into the circular flow of income. It is calculated as 1 ÷ (1 − MPC) or 1 ÷ (MPS + MPT + MPM).

Imagine the UK government spends £1 billion building new hospitals. The construction firms receive that £1 billion. Their workers get paid. Those workers then spend money at supermarkets, restaurants, and shops. Those businesses then pay their employees, who go out and spend again. And so on.

The original £1 billion ends up creating far more than £1 billion of economic activity. That's the multiplier in action.

The Keynesian multiplier shows that any increase in injections into the circular flow results in a proportionately larger increase in AD.

The Formulas (Yes, You Need These)

There are two ways to calculate the Keynesian multiplier:

Formula 1:

Keynesian Multiplier = 1 ÷ (1 − MPC)

Formula 2:

Keynesian Multiplier = 1 ÷ (MPS + MPT + MPM)

If MPC = 0.8, the multiplier = 1 ÷ (1 − 0.8) = 5.

That means every £1 the government spends generates £5 of economic activity. Not bad, right?

What Are Injections and Leakages?

The multiplier works through injections - the three sources of extra spending flowing into the circular flow:

• G (Government spending)

• I (Investment)

• X (Export earnings)

But money also leaks out of the circular flow through withdrawals:

• S (Savings - money not spent)

• T (Taxes - money taken by the government)

• M (Imports - money spent abroad, not on domestic goods)

The more money leaks, the weaker the multiplier. Similar to a chain of dominoes - every time someone saves instead of spends, or buys a foreign product instead of a domestic one, the chain of spending gets cut short.

What Determines the Multiplier? (HL)

Four key concepts determine how big - or small - the multiplier effect is:

1. Marginal Propensity to Consume (MPC)

MPC = ΔC ÷ ΔY

This measures the proportion of every extra pound earned that gets spent on goods and services. If you earn an extra £100 and spend £80, your MPC = 0.8.

The higher the MPC, the larger the multiplier - more spending means further economic activity.

So, the marginal propensity to consume (MPC) is the proportion of each additional unit of income that a household spends on goods and services, calculated as ΔC ÷ ΔY.

During recessions, lower-income households tend to have higher MPCs because they have little savings buffer. This is why targeted spending towards poorer households - like the UK's uplift to Universal Credit - can be genuinely effective as stimulus.

2. Marginal Propensity to Save (MPS)

MPS = ΔS ÷ ΔY

Money that's saved doesn't circulate through the economy in the same way. The higher the MPS, the more money leaks out, and the smaller the multiplier. Rich households tend to have high MPSs - which is one reason tax cuts for the wealthy are often seen as weaker stimulus than direct spending.

3. Marginal Propensity to Import (MPM)

MPM = ΔM ÷ ΔY

This measures how much of extra income gets spent on imports - goods and services produced abroad. If British consumers spend their extra income on American iPhones or German cars instead of UK-made products, that money leaves the UK economy. For small, open economies with high import propensities (think Ireland, or many Caribbean nations), the multiplier can be incredibly weak.

4. Marginal Propensity to Tax (MPT)

MPT = ΔT ÷ ΔY

Every pound taxed is a pound that doesn't flow back into consumption. Higher tax rates reduce the multiplier. This is why governments in deep recessions sometimes cut taxes - even at the cost of short-term revenue - to keep the multiplier as high as possible.

IB Economics Real-Life Example: on Multipliers

Research by economists Auerbach and Gorodnichenko found that a $1 increase in US government spending raises output by approximately $1.50 to $2.00 in a recession, but only about $0.50 in a period of expansion. In other words, the multiplier is much more powerful when the economy has spare capacity - exactly what the Keynesians have claimed for many years.

In the US, measures like food assistance (SNAP) and unemployment insurance are estimated to have multipliers of around $1.50 - meaning every dollar spent generated roughly $1.50 of economic output. Why? Because recipients have high MPCs and spend the money quickly.

Constraints on Fiscal Policy:

Expansionary fiscal policy sounds at times too good to be true and that's partly because it has serious limitations. Here are some things that can go wrong:

1. Political Pressures

Economics and politics don't always mix well. Tax cuts are popular with voters regardless of whether they're economically justified or not. Governments sometimes cut taxes or increase spending to win elections rather than to solve genuine economic problems. The temptation to be politically popular and earn extra votes rather than applying economical sense happens more often than desired.

2. Time Lags

Fiscal policy is notoriously slow. Tax changes require legislation. Infrastructure projects take years to plan, approve, and build. By the time the stimulus actually hits the economy, the recession might already be over - meaning you've added fuel to a recovery process that didn't need it. This is one reason why economists talk about fiscal policy being "timely, temporary, and targeted."

3. Sustainable Debt

Running a budget deficit (G > T) is fine in the short run - governments borrow all the time. But it's not sustainable forever. National debts must eventually be repaid, which at the same time limits future spending flexibility.

UK government debt stood at 93.6% of GDP at the end of 2024/25, and the OBR forecasts it will rise to 97% of GDP by 2028/29 before gradually falling. That's little room for future fiscal firepower.

4. Crowding Out (HL)

This is arguably the most important - and most examined - constraint at HL level.

Crowding out occurs when increased government borrowing causes interest rates to rise, which in turn reduces private sector investment.

So, crowding out occurs when increased government borrowing raises interest rates, reducing private sector investment and partially offsetting the stimulus effect of expansionary fiscal policy.

Here's the idea:

• Government increases spending → needs to borrow more → increased demand for loanable funds

• More demand for borrowing → interest rates rise

• Higher interest rates → borrowing is more expensive for firms → private investment (I) falls

• So G goes up, but I goes down - partially cancelling out the stimulus

On the loanable funds diagram, the supply of funds is fixed (vertical), so when government borrowing demand increases, it pushes interest rates from r₁ → r₂, crowding private borrowers out of the market.

New classical economists use this exact criticism against expansionary fiscal policy - they argue it doesn't stimulate the economy net; it just shifts who's spending (public sector crowds out private sector).

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Strengths of Fiscal Policy: When It Actually Works

Despite several limitations, fiscal policy has genuine strengths:

1. Targeting Specific Sectors

Unlike monetary policy (which affects all borrowing equally), fiscal policy can be more specific. Tax cuts for low-income earners only. Extra NHS spending. Housing vouchers for first-time buyers. Infrastructure investment in specific deprived regions. This precision is particularly valuable for addressing regional economic disparities or specific sectors of the population.

2. Effective in Deep Recessions

When the economy is in genuine crisis - a Great Depression, a pandemic, a financial crash - fiscal policy is often the only tool with enough power to change things around. Interest rates can hit zero (the famous "liquidity trap"), making monetary policy ineffective. But the government can still spend. During the COVID-19 pandemic, fiscal policy boosted US real GDP by approximately 4% in the second, third, and fourth quarters of 2020 - directly soothing the worst part of the economic crisis.

3. Automatic Stabilisers (HL)

Automatic stabilisers are features of the fiscal system that automatically reduce economic fluctuations without any new government initiative or decision-making. They intervene precisely when needed.

So, automatic stabilisers are features of the tax and benefit system - primarily progressive taxation and unemployment benefits - that automatically dampen economic fluctuations without the need for new government decisions.

Two main types:

Progressive Taxes: During a boom, rising incomes push people into higher tax brackets - so the government automatically collects more tax revenue, cooling demand without anyone having to legislate anything. During a recession, falling incomes mean lower tax bills, automatically leaving more money in people's pockets.

Unemployment Benefits: When a recession hits and people lose jobs, benefit payments automatically rise - cushioning the fall in disposable income and preventing the economy from collapsing further. When employment recovers, benefit spending naturally falls without any active decision needed.

Automatic stabilisers are highly efficient because they have no implementation lag - they work instantly, every time. Keynesian economists argue they are crucial to preventing deep recessions from going further and becoming catastrophic ones.

In the UK, the extended freeze on income tax thresholds (keeping the personal allowance at £12,570 and the higher rate threshold at £50,270) is a form of fiscal drag - a passive form of progressive taxation that automatically raises the government's tax take at the same time as nominal incomes rise with inflation. The extension of the personal tax threshold freeze to 2031 is expected to raise £23 billion in total by 2030/31 - all without the government actively touching or raising tax rates.

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Not Just Any Debate: Keynesians vs Monetarists

The debate over fiscal policy is usually a war between two worldviews:

Keynesians say: The economy can get stuck below full employment. Markets don't always self-correct. Governments must intervene with spending to close recessionary gaps. The multiplier amplifies the impact. Automatic stabilisers provide a safety net.

Monetarists/New Classicals say: Expansionary fiscal policy is ultimately self-defeating. Crowding out neutralises private investment. In the long run, all you've done is raise the price level, you have not increased real output. Better to use supply-side policies to shift the LRAS outward - train workers, cut red tape, improve incentives.

Both sides have evidence. Neither side is completely right. And that ambiguity is exactly what makes this debate such a rich topic for IB Economics exam essays.

Frequently Asked Questions

Q1: What is the difference between expansionary and contractionary fiscal policy? Expansionary fiscal policy increases government spending and/or cuts taxes to boost aggregate demand during a recession. Contractionary fiscal policy does the opposite - cutting spending and/or raising taxes to reduce demand and combat inflation during a boom.

Q2: What is the Keynesian multiplier and how is it calculated? The Keynesian multiplier shows that an initial injection into the economy generates a proportionally larger increase in GDP. It is calculated as 1 ÷ (1 − MPC) or 1 ÷ (MPS + MPT + MPM). A higher MPC means a larger multiplier and a greater stimulus effect.

Q3: What are the main limitations of fiscal policy? The main constraints are: political pressures (governments may prioritise votes over economics), time lags (policy takes time to implement), sustainable debt (deficits can't run indefinitely), and crowding out (government borrowing may raise interest rates, reducing private investment).

Q4: What is crowding out in IB Economics? Crowding out occurs when a government increases borrowing to fund spending, driving up interest rates. This makes borrowing more expensive for businesses, reducing private sector investment - cancelling out the stimulus effect partially.

Q5: What are automatic stabilisers and why are they important? Automatic stabilisers - mainly progressive taxes and unemployment benefits - reduce economic volatility without any new policy decisions. They work instantly: during booms, higher tax revenues cool demand; during recessions, benefit payments cushion falling incomes. They have no implementation lag, making them arguably the most reliable feature of fiscal policy.

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More Information About:

IB Economics Hub Page your IB Economics daily guide

IB Economics Macroeconomics Hub Page access Fiscal Policy here as well as the rest of module 3

IB Economics Diagrams Page Check Unit 23 for All Fiscal Policy diagrams with explanations

IB Economics Activity book Page Module 3 Macroeconomics Unit 3.14 for Fiscal Policy exam practice, activities, model answers and IB Economics Marking schemes

IB Economics The Business Cycle Hub Page is directly related to recession/boom need to know the effects of these economic stages in detail

IB Economics Monetary Policy Hub Page for exploring in depth concepts related to Interest rates and crowding out

IB Economics Unemployment Hub Page strong relationship with deflationary / recessionary gap

IB economics Calculations Book make sure you check unit 22 for Fiscal Policy calculations exercises, IB model answers, and IB marking schemes

IB Economics Supply-side Policies post strong and direct relationship to the monetarist critique

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