Fiscal choices, deficits and debt dynamics

Learning goals

• Distinguish fiscal instruments from monetary instruments.
• Analyze discretionary changes, automatic stabilizers and debt sustainability assumptions.

Draft · approximately 45 minutes, excluding further revision.

Measure the policy change, not just the deficit

Fiscal policy uses government spending, transfers and taxation to affect allocation, distribution and aggregate activity. Monetary policy primarily influences money, credit and financing conditions through the central bank’s framework. A larger deficit can arise automatically when activity weakens and tax receipts fall, even without a new discretionary stimulus. Distinguish the observed balance from a cyclically adjusted estimate, which itself depends on uncertain potential-output assumptions.

A simple closed-economy model with a fixed price level, no crowding out and constant marginal propensity to consume c gives spending multiplier 1/(1−c) and tax multiplier −c/(1−c). Imports, taxes that rise with income, capacity limits, financing reactions and expectations can reduce or change those effects. Multipliers are model-dependent, not promises about actual GDP. Transfers influence demand through recipients’ behavior rather than being government purchases directly.

Debt sustainability is a conditional trajectory

A useful debt-ratio identity is bₜ=[(1+i)/(1+g)]bₜ₋₁−primary surplus/GDPₜ, using nominal interest i and nominal GDP growth g with compatible timing and ignoring valuation adjustments. Interest above growth creates upward pressure, but a primary surplus can offset it. Currency composition, maturity, contingent liabilities, the tax base and credibility matter; no single universal debt/GDP threshold determines default.

Recognition, legislative and implementation lags can cause stimulus to arrive after the original need. Productive investment may support future capacity but still requires project selection and financing. Fiscal expansion can raise demand and interest rates; the actual result depends on spare capacity, monetary response and external funding conditions. Separate policy intent from demonstrated effect.

Formula and assumptions

Spending multiplier = 1/(1−c) under simplified assumptions; bₜ = [(1+i)/(1+g)]bₜ₋₁ − primary surplus/GDPₜ

A multiplier and a debt-ratio sensitivity

1. Under the explicitly simplified model, c=0.75 gives spending multiplier 4. A spending increase of 10 raises model output by 40, before other feedbacks.
2. Debt/GDP starts at 60%; nominal interest=6%, nominal growth=4%, primary surplus=1% of current GDP. Next ratio=1.06/1.04×0.60−0.01=60.1538%.
3. If growth instead reaches 6%, the ratio becomes 59%. This sensitivity is not a forecast and excludes exchange-rate and other valuation changes.

Calculation lab

Errors to catch

• Calling every larger deficit a discretionary easing.
• Mixing real growth with nominal interest in the debt identity.

Original knowledge check

Answer every question before checking. Review explanations after submitting; retry starts a new attempt.

Sources and coverage status

These original lessons are drafts. Public outlines are used to check scope; the official learning-outcome text and proprietary question banks are not reproduced here. Follow the source for exam-year requirements and updates.

• Reference · www.cfainstitute.org