Debt, discipline, and doubt in central bank independence
Luigi Bocola, Gaston Chaumont, Alessandro Dovis, and Rishabh Kirpalani analyze what happens to the joint dynamics of inflation and public debt central bank independence is not automatically credible.
The authors build a Sargent-Wallace-style model in which a government would like to delegate monetary policy to an independent, inflation-targeting central bank, but cannot fully commit to leaving that independence intact. Ex-post, the government always retains the option to override the central bank’s mandate and generate seigniorage revenue. The question is then how costly that override is, and that cost is precisely what the model treats as central bank independence.
To measure this credibility empirically, the authors calibrate the model to Latin American economies (1960–2017) and use particle filter methods to infer, period by period, how credible central bank independence was in Chile and Colombia, based on observed inflation and debt-to-GDP data. They later extend the narrative to the U.S. Federal Reserve in the 1970s–1980s.
Findings
The central theoretical result is that central bank independence and public debt are locked in a two-way relationship: credible independence is what allows a government to sustain high debt levels in the first place, yet high debt itself endogenously undermines that same independence by raising the government’s temptation to override the mandate for seigniorage. This creates two distinct regimes:
- A monetary-dominant regime, where central bank independence holds, inflation is low and insulated from fiscal pressures, and debt-to-GDP can run high.
- A fiscal-dominant regime, where the government overrides the central bank, inflation runs high, is volatile, and tightly linked to fiscal conditions, while debt is comparatively low.
- The model also isolates two very different disinflation channels, distinguished entirely by what they imply about central bank independence: fundamental disinflation (falling debt, driven by reduced government spending needs, independent of any change in institutional credibility) versus institutional disinflation (rising debt, driven specifically by an increase in the credibility of central bank independence, which frees the government to borrow more without fear of triggering an override).
Applying this lens to real economies:
Colombia is a textbook case of an institutional disinflation:— inflation fell sharply while debt rose, and the model detects a genuine jump in central bank independence credibility only in 1997, five years after the 1992 legal reform that nominally granted independence.
Chile shows primarily a fundamental disinflation via fiscal consolidation, but the model finds that credibility gains in central bank independence were still necessary to explain continued disinflation in the late 1990s even as debt merely stabilized.
The United States illustrates the same logic in reverse and then forward: the Great Inflation of the 1970s reflects a collapse in the Federal Reserve’s de facto independence under political pressure, while the Volcker era marks a gradual rebuilding of that independence which, once restored, permitted debt to rise from the mid-1980s onward while inflation stayed low and stable.
On optimal policy, the authors show that when central bank independence is imperfectly credible, it is optimal for the government to set a higher inflation target than under full commitment and to issue less debt than it otherwise would, precisely to reduce the temptation to erode that independence later. Both distortions grow larger when the government’s spending needs are high, existing debt is already high, or the institutional/political cost of overriding the central bank is low.
Accounting for Credibility: Fiscal-Monetary Interactions and the Credibility of Central Bank Mandate
Authors: Luigi Bocola, Gaston Chaumont, Alessandro Dovis, Rishabh Kirpalani
From: Stanford University, University of Rochester, §University of Pennsylvania, University of Wisconsin
How rising public debt narrows the room for independent central banks
Isabel Schnabel’s speech argues that central bank independence faces a dual threat: direct political attacks combined with structural forces quietly eroding the conditions for effective independent monetary policy, chief among them rising public debt.
The fiscal dominance mechanism
She notes that advanced-economy debt is now at or near post-WWII highs, with structural forces (aging populations, defense spending, green/digital transition costs) likely to push it higher still. Illustrative simulations suggest euro area debt-to-GDP could rise over 30 percentage points by 2050 due to aging alone.
Why debt now threatens independence more acutely
Schnabel highlights a shift in bond market structure that amplifies the fiscal-monetary tension: hedge funds and other price-sensitive investors now account for roughly a third (or more) of secondary trading in US Treasuries and euro area sovereign debt, making demand for long-duration government debt less reliable. She notes many governments have responded by shortening debt maturities, meaning the fiscal consequences of monetary tightening are now felt “faster and more acutely” as the insulation once provided by longer maturities is eroding. She warns that if doubts about fiscal trajectories intensify, sovereign term premia could rise further, potentially constraining monetary policy since higher policy rates could themselves threaten fiscal sustainability.
Proposed safeguards
Schnabel argues fiscal dominance is not inevitable and can be mitigated through credible fiscal frameworks: enforced fiscal rules (not suspended at every shock), spending redirected toward growth-enhancing areas (infrastructure, green/digital transition), and a credible consolidation path so that fiscal policy remains aligned with monetary policy rather than forcing central banks into more forceful, costlier tightening later.
