Fiscal Policy
Fiscal policy is the government's use of public spending and taxation to steer activity—stimulus, multiplier, deficit and debt. Mankiw presents it as the second major lever of macroeconomic policy, complementary to monetary policy, with potentially more direct effects on aggregate demand but also long-term sustainability constraints.
Last updated: 9 July 2026
Definition
DefinitionFiscal policy encompasses all government decisions regarding its revenues (taxes, duties, social contributions) and expenditures (administrative operations, public investment, social transfers).
The fiscal balance is the difference between revenues and expenditures: when spending exceeds revenue, the budget is in deficit and the government must borrow to finance the difference. The accumulation of these borrowings constitutes public debt.
A distinction is drawn between discretionary fiscal policy (deliberate government decisions to change spending or taxes) and automatic stabilizers (budgetary mechanisms that activate without political decisions, such as rising unemployment benefits during a recession or falling tax revenues when activity slows).
Why it matters
Mankiw presents the debate between Keynesians and classicals as one of the oldest and most structuring in macroeconomics. Keynesians argue that expansionary fiscal policy is an effective tool for exiting a recession, because the multiplier is high when the economy operates below potential and interest rates are near zero (when monetary policy is less effective). Classicals and proponents of Ricardian equivalence consider that public borrowing merely shifts the burden over time without creating net wealth.
Mankiw notes that the answer depends on the time horizon: in the short run, when unused productive capacity exists, fiscal stimulus can indeed boost output. In the long run, chronic deficits increase debt, push up interest rates, and reduce private investment through crowding out, penalizing potential growth.
Key points
The fiscal multiplier is higher in recessions than in expansions, and higher for direct public spending than for tax cuts, because part of the tax cuts is saved by households rather than consumed
Automatic stabilizers represent a first line of defense against recessions, with no political implementation delay. Mankiw describes them as the "autopilots" of fiscal policy
The debt-to-GDP ratio tends to decline when the nominal GDP growth rate (g) exceeds the average interest rate paid on debt (r), at a balanced primary budget. Formally: Δ(D/Y) ≈ (r − g) × (D/Y) − primary balance (revenues minus expenditures excluding interest). Otherwise (r > g), the ratio rises mechanically, even with a balanced primary budget ("snowball" dynamics)
The government's intertemporal budget constraint implies that the present value of its future primary surpluses must be at least equal to its current debt for it to be sustainable
Concrete example
ExamplesThe post-Covid European recovery plan "NextGenerationEU" (€750 billion in 2018 prices, around €807 billion in current prices, from 2021 to 2026), financed for the first time at this scale by joint EU borrowing, illustrates coordinated expansionary fiscal policy at the supranational level. In France, the "whatever it costs" approach brought the public deficit to nearly 9% of GDP in 2020 (8.9%) and debt to nearly 115% of GDP (114.6%). In 2024, French debt stands at 113% of GDP and the deficit at 5.8% (source: INSEE)—well above the 3% limit set by the Stability Pact, which was reformed in 2024 (the 3% and 60% thresholds were kept, but governance now runs through multi-year net-expenditure paths).
Mankiw anecdote
MankiwMankiw often sums up the debate between Keynesians and classicals with a simple idea: in the short run, the Keynesian analysis frequently applies; in the long run, it is rather the classical conclusions that prevail. He emphasizes that the 2008–2009 crisis rehabilitated fiscal stimulus policies in academic circles, after a period when macroeconomic stabilization was mainly entrusted to monetary policy. The debate over the size of the multiplier (greater or less than 1?) remains one of the liveliest in applied macroeconomics.
Further reading
ProgressionDebt sustainability dynamics, the r − g equation, the deficit bias of democracies, and sovereign default mechanisms are explored in depth in the "Political Economy of Public Debt" sheet (Ch. 15, Advanced level).
Market impact
MarketsFiscal policy announcements primarily influence bond markets: an increase in the deficit raises the supply of sovereign debt, which can push up bond yields (and hence the government's borrowing costs). A persistent deficit can weaken the national currency if investors doubt debt sustainability. Massive stimulus plans support equity markets in the short term by boosting activity, but raise sustainability questions that can weigh on long-term bonds.