Monetary Policy, Inflation, and the Role of Backed vs Unbacked Public Debt

In the evolving landscape of macroeconomic policymaking, the interaction between monetary and fiscal policy has become increasingly critical – especially in the context of rising global debt, persistent inflation, and tightening financial conditions. The paper titled “ The Effects of Monetary Policy Shocks on Inflation: The Role of Backed and Unbacked Public Debt in a Monetary and Fiscal Policy Regime Mix ” provides valuable insight into how monetary policy transmits to inflation through its interaction with different types of public debt and fiscal commitments. Theoretical Framework and Regimes The paper builds on the fiscal theory of the price level (FTPL), which recognises that inflation can be driven not only by monetary policy but also by fiscal imbalances – particularly when public debt is not fully backed by future fiscal surpluses. Traditional models typically analyse two regimes. The first one is Regime M (Monetary dominance): The central bank controls inflation while the fiscal authority adjusts surpluses to stabilise public debt. The second regime is Regime F (Fiscal dominance): The fiscal authority determines the path of public debt without committing to debt stabilisation, leaving the central bank to accommodate the fiscal authority’s policy stance and does not control inflation. However, these two extremes often fail to reflect real-world complexities. As a middle-ground alternative, the study investigates a coexistence regime, where public debt is split into backed and unbacked components. Backed debt is expected to be repaid through future fiscal surpluses (Regime M), while unbacked debt is stabilised via inflation (Regime F). Key Findings We simulate how a contractionary monetary policy shock affects inflation and debt dynamics under the three regimes. Under the coexistence regime, inflation rises less than under Regime F and public debt increases less than under Regime M. This outcome results from a balanced response: some debt is absorbed th