欧洲央行-公共债务、iMPC和财政政策传导（英）

Working Paper Series Public debt, iMPCs & fiscal policy transmission Stefano Grancini Disclaimer: This paper should not be reported as representing the views of the European Central Bank (ECB). The views expressed are those of the authors and do not necessarily reflect those of the ECB. No 3106 AbstractThis paper investigates the relationship between public debt and the effectiveness of fiscalpolicy, presenting evidence of an inverse relationship between government debt and fiscalmultipliers. To explain the results, I develop and calibrate a HANK model tailored to the U.S.economy. The model reveals that higher public debt diminishes fiscal multipliers by mak-ing households less constrained. Theoretically, I show intertemporal marginal propensitiesto consume (iMPCs) are sufficient statistics of public debt, influencing fiscal multipliers. De-composing changes in iMPCs into components driven by wealth distribution and the policyfunction, I find that the primary factor driving variations in iMPCs is the change in interestrates due to the variation of government bonds. This highlights a novel mechanism: even inthe absence of fiscal limits or crowding out, large stocks of debt can weaken fiscal stimulusthrough their effect on household behavior.JEL Codes: E21; E62; E43; D31; D52Keywords: Fiscal multipliers; Government bonds; Consumption heterogeneity; Interest rates; Wealth effectsECB Working Paper Series No 31061Non-technical summaryRecent years have brought renewed attention to fiscal policy, particularly in countries experi-encing high levels of public debt. Against this backdrop, this paper asks a central question:does the presence of large government debt make fiscal policy less effective in stimulatingthe economy? Presenting new empirical evidence and using a state-of-the-art macroeconomicmodel, the paper finds that higher public debt tends to weaken the impact of governmentspending on output. This conclusion has important implications for countries carrying signif-icant debt and seeking to use government spending to stabilize or boost economic activity.Following the global financial crisis of 2008 and the subsequent large-scale policy re-sponses, many governments increased their spending. These measures were often financedby issuing government bonds, leading to historically high public debt levels in advancedeconomies. The core goal of this research is to show how such debt may affect the so-called“state-dependent fiscal multiplier” — that is, the degree to which a given amount of extragovernment spending translates into higher economic output, for different levels of debt.Empirical analysis using U.S. data shows that fiscal multipliers (the additional outputgenerated by each euro or dollar of public spending) tend to be smaller when public debt ishigh. A variety of statistical tests confirms that this finding is robust to different assumptionsand potential sources of bias. When the debt-to-GDP ratio is relatively high, the boost froman incre