Ch6. Fiscal Policy — Multipliers, Crowding Out, and Fiscal Sustainability

The Tools of Fiscal Policy

The federal government uses two fiscal instruments to manage the economy.

Tool	Expansionary	Contractionary
Government spending	Increase spending	Cut spending
Taxes	Cut taxes	Raise taxes

The core mechanism of fiscal policy: the multiplier effect

Fiscal Multiplier Theory

Government Spending Multiplier

When the federal government spends an additional $100 billion, GDP rises by more than$ 100 billion.

Why: Spending generates income, which generates consumption, which generates more income — a chain reaction.

Government spending multiplier = 1 / (1 − MPC)

Where MPC = marginal propensity to consume (fraction of additional income spent on consumption)

Calculation example:

MPC = 0.8 → multiplier = 1/(1−0.8) = 5
$100 billion in government spending →$ 500 billion increase in GDP

Tax Multiplier

Cutting taxes by $100 billion increases GDP — but by less than the spending multiplier.

Tax multiplier = −MPC / (1 − MPC)

Calculation example:

MPC = 0.8 → tax multiplier = −0.8/0.2 = −4
$100 billion tax cut →$ 400 billion increase in GDP

Why the spending multiplier exceeds the tax multiplier:

Government spending injects the full dollar into demand immediately
A tax cut only partially translates to spending (households save a fraction = 1 − MPC)

Balanced-Budget Multiplier

What happens when Congress raises taxes and increases spending by the same amount?

Balanced-budget multiplier = spending multiplier + tax multiplier
                            = 1/(1−MPC) + (−MPC/(1−MPC))
                            = 1

Balanced-budget multiplier = 1: A deficit-neutral increase in government spending raises GDP by exactly the amount of the spending increase.

Automatic Stabilizers

Built-in features of the fiscal system that reduce output swings without any new legislation.

Types and Mechanisms

Progressive income tax:

Expansion → incomes rise → taxes automatically increase → dampens overheating
Recession → incomes fall → taxes automatically decrease → supports spending

Unemployment Insurance (UI):

Recession → unemployment rises → UI benefits automatically increase → supports consumer spending
Expansion → unemployment falls → UI spending automatically decreases → fiscal improvement

Advantages of automatic stabilizers:

No implementation lag (no congressional action required)
No political decision required
Automatically smooth the business cycle

Limitation: Magnitude is weaker than discretionary policy; deep recessions require additional stimulus

Ricardian equivalence: If the government cuts taxes and finances spending with debt, rational taxpayers anticipate higher future taxes and save the tax cut rather than spending it. Therefore, a deficit-financed tax cut has no stimulative effect on consumption.

Assumptions

Consumers fully anticipate the future tax increase implied by current deficits
Perfect capital markets (no borrowing constraints)
Infinite horizon or bequest motive (consumers care about future generations)

Implications

Tax cuts do not stimulate consumption
Whether deficits are financed by taxes or bonds is economically equivalent
Discretionary fiscal policy via tax cuts is ineffective

Real-World Limitations

Most economists believe Ricardian equivalence does not hold strictly.

Counterarguments:

Liquidity constraints: Low-income households cannot borrow against future income → they spend tax cuts
Myopic behavior: Consumers don’t fully discount future taxes → tax cuts do stimulate spending
Evidence: Tax rebates (e.g., 2001, 2008 stimulus checks) did increase consumer spending

Crowding Out

Crowding out: Government spending increases → Treasury borrowing increases → interest rates rise → private investment decreases

Mechanism

Government deficit ↑ → Treasury issues more bonds
→ Demand for loanable funds increases
→ Interest rates rise
→ Private investment falls (higher cost of capital)
→ Fiscal stimulus partially offset

Complete Crowding Out

Complete crowding out occurs when the LM curve is vertical or the IS curve is vertical.

Vertical LM curve: Money demand is perfectly interest-inelastic → fiscal policy has no effect (classical model)
Vertical IS curve: Investment is perfectly interest-inelastic → no crowding out (Keynesian extreme)

Reality: Complete crowding out is rare; partial crowding out is the norm.

Small Open Economy

In a small open economy where interest rates are determined internationally:

Fiscal expansion → upward pressure on domestic interest rates → capital inflows
Currency appreciates → exports fall
Complete crowding out of net exports (Mundell-Fleming model): fiscal policy ineffective on GDP

National Debt: Economic Effects

US National Debt Context

US federal debt held by the public: approximately $27–28 trillion (roughly 100% of GDP as of 2024). Interest costs have risen significantly with higher interest rates.

Problems with Persistent Deficits

Intergenerational equity: Current generations spend; future generations repay — a distributional concern.

Crowding out of investment: Deficit spending → higher interest rates → less private capital formation → lower long-run growth.

Debt crisis risk: If the debt-to-GDP ratio rises unsustainably, credit ratings fall → interest rates rise → debt service costs spiral (self-reinforcing dynamic).

Fiscal Sustainability Condition

The debt-to-GDP ratio stabilizes when:

Primary deficit / GDP ≤ (r − g) × (Debt / GDP)

Where r = real interest rate, g = real GDP growth rate.

If GDP growth exceeds the real interest rate (g > r), the government can run primary deficits without an ever-rising debt ratio.

Fiscal Rules

Fiscal rules: Legal or institutional constraints on government fiscal behavior.

Type	Content	Example
Balanced-budget rule	Limit on deficits (as % of GDP)	Most US states; Germany’s debt brake
Debt ceiling	Cap on total debt outstanding	US statutory debt ceiling
Expenditure rule	Limit on spending growth	Sweden’s surplus target

US context:

The US debt ceiling is a statutory cap on total federal debt; it does not directly limit deficits
CBO provides independent budget projections and fiscal sustainability analysis
No binding federal balanced-budget rule (unlike most US states)

Frequently Tested Concepts

Multiplier calculations:

Government spending multiplier = 1/(1−MPC)
Tax multiplier = −MPC/(1−MPC)
Balanced-budget multiplier = 1

Automatic stabilizers:

Progressive income tax + unemployment insurance — the two main examples
Operate without legislative action

Ricardian equivalence:

Tax cut → saving increase → consumption unchanged → fiscal policy ineffective
Doesn’t hold fully in practice

Crowding out:

Deficit → higher interest rates → less private investment
Stronger in a small open economy (Mundell-Fleming)

Study Checklist

Calculate the government spending multiplier and tax multiplier given MPC
Derive the balanced-budget multiplier and explain why it equals 1
Explain how automatic stabilizers work with no new legislation
Describe Ricardian equivalence and why it fails in practice
Explain the crowding-out mechanism and when it is most severe