Public Debt Dynamics and the Impact of Fiscal Policy

IMF Working Papers, April 26, 2024

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Public debt-to-GDP ratios have undergone substantial fluctuations over both the short and long term.
Global debt-to-GDP ratios peaked at 100% on average in 2020 due to COVID-19, retracting substantially by 2022.
Using a structural approach to debt decompositions based on a SVAR identified with narrative sign restrictions, the study finds:
- GDP growth shocks and the corresponding comovements of macroeconomic variables account for 40% of the observed yearly variation in 17 advanced economies since the 1980s.
- Discretionary fiscal policy changes account for less than 20% of the observed changes in debt-to-GDP.
- The primary balance multiplier on GDP is found to be very small.

Structural vector autoregression (SVAR) identified with narrative sign restrictions is the core empirical approach used to decompose drivers of public debt dynamics.
Emphasis on accurate shock identification and accounting for cross-country heterogeneity as key elements in reconciling results with existing literature.

Peak global debt-to-GDP: 100% (in 2020).
Retracted substantially by 2022.
Contribution of GDP growth shocks to yearly variation in debt-to-GDP: 40 percent.
Sample scope: 17 advanced economies.
Sample time span reference: since the 1980s.
Contribution of discretionary fiscal policy changes: less than 20 percent.
Primary balance multiplier on GDP: described as very small.

Macroeconomic shocks (in particular GDP growth shocks) and their comovements with other macro variables are the dominant drivers of public debt fluctuations in advanced economies.
Discretionary fiscal policy changes play a smaller role than commonly perceived in year-to-year debt dynamics.
Because the primary balance multiplier on GDP is very small, fiscal consolidation via discretionary measures may have limited immediate effects on debt-to-GDP ratios relative to the impact of macroeconomic growth developments.
Policy analysis and advice should account for:
- Precise identification of shocks in empirical work.
- Cross-country heterogeneity in debt dynamics and fiscal responses.

Public Debt Dynamics and the Impact of Fiscal Policy — Nikhil Patel, April 26, 2024.