Sovereign Debt Restructuring and Reduction in Debt-to-GDP Ratio

Layer 1: Overview

Sovereign debt restructuring is a central tool for countries in debt distress, yet surprisingly little evidence exists on whether it actually reduces the debt-to-GDP ratio — the metric used in virtually every debt sustainability analysis. This paper fills that gap. The debt-to-GDP ratio is not a simple pass-through from restructuring: the numerator (debt stock) only falls at the completion of a restructuring episode, while the denominator (GDP) can be depressed from the start of the crisis. Cash flow relief and face value reductions affect the numerator along different timelines, and fiscal consolidation — or its absence — can erode or reinforce whatever gains restructuring provides. These complexities make the net effect on the ratio genuinely non-obvious.

The authors compile a novel, highly comprehensive dataset covering 709 restructuring events across 115 emerging market and developing economies from 1950 to 2021, encompassing private external creditors, Paris Club bilateral creditors, China, and domestic creditors — broader coverage than any prior study. Country-level macroeconomic data (GDP, general government debt, primary balances, inflation, exchange rates) come from the IMF World Economic Outlook October 2022 vintage. The sample excludes advanced economies, which almost never restructure (the three AE episodes — Slovenia 1992–96, Greece 2011–12, Cyprus 2013 — are dropped because the structural features of AE debt differ markedly from EMEs and LICs).

Identification addresses the core problem that restructuring is endogenous to macroeconomic conditions: countries restructure precisely when growth is weak and fiscal positions are deteriorating. Following Jorda and Taylor (2016), the authors employ an Augmented Inverse Probability Weighted (AIPW) estimator. A first-stage saturated probit model estimates each country-year’s propensity score using lagged GDP growth, debt-to-GDP levels (interacted with country dummies to allow heterogeneous thresholds), primary and current account balances, US short and long interest rates, effective interest rates, and prior restructuring history. The predicted propensity scores feed a second-stage local projection of debt-to-GDP changes on the restructuring dummy and covariates across horizons 0–5 years. The AIPW is doubly robust: consistency requires only that the first stage or the second stage (not necessarily both) be correctly specified. The propensity model achieves an AUROC above 0.85.

The main finding is that a typical sovereign debt restructuring event reduces the debt-to-GDP ratio by 3.8 percentage points in the first year (statistically significant), rising to a cumulative 7.2 percentage points after five years. The effect is negative and significant at every horizon from year 0 through year 5, and extends beyond five years (robustness checks to 10-year horizon show consistently negative effects, though standard errors widen with smaller samples). An important robustness check using debt level (percent change in debt stock) as the outcome shows the restructuring reduces debt by about 7 percent on impact and over 35 percent after five years — establishing that the ratio result is not mechanically driven by GDP movements alone.

Heterogeneity across restructuring types and accompanying policies is substantial. When restructuring coincides with fiscal consolidation (positive average cyclically adjusted primary balance during the episode), the debt-to-GDP decline ranges from 4.7 percentage points in year 1 to 11.9 percentage points in year 5 — roughly double the average effect in the long run. Restructurings that include a face value reduction show an immediate impact of 8.9 percentage points in year 1 (versus 3.8 for the average), but the long-run effect after five years converges toward 5.0 percentage points — smaller than the fiscal consolidation pathway. Large-scale creditor coordination under the HIPC/MDRI initiatives produces ATEs of 5.4 percentage points in year 1 and 6.4 percentage points in year 5. These results collectively indicate that the long-run depth of the debt reduction is most reliably achieved when restructuring is paired with sustained fiscal effort, whereas face value reduction and creditor coordination are particularly potent in the short run.

A novel finding concerns cash flow relief only (maturity extension and/or coupon rate reduction, without face value reduction): normalizing by the size of treatment (the average present-value reduction in the debt ratio, estimated at 2.8 percentage points of GDP for private external restructurings, compared to 6.0 percentage points for face value reduction events), the ATE per unit of treatment for cash flow relief converges to roughly the same magnitude as for face value reduction after four to five years. This suggests that, conditional on treatment depth, the form of restructuring does not determine long-run effectiveness — what matters is that the intervention provides sufficient fiscal space for subsequent adjustment.

Layer 2: Deep Dive

What is the identification strategy, and what are the main threats to it?

The paper uses an Augmented Inverse Probability Weighted (AIPW) estimator following Jorda and Taylor (2016). The first stage is a saturated probit model predicting the propensity score for restructuring entry using: two lags of the treatment dummy, GDP growth, and change in debt-to-GDP; one lag of exchange rate change, inflation, global output gap, US short and long rates, effective interest rate, primary balance, and current account balance; and the level of debt-to-GDP interacted with country dummies (to allow heterogeneous restructuring thresholds). The second stage is a local projection of the change in debt-to-GDP regressed on the treatment dummy, its interaction with covariates, and country plus year fixed effects, across horizons 0–5. The AIPW ATE formula re-weights observed outcomes by propensity scores and adds augmentation terms from the outcome model, yielding double robustness. The main identification threat is selection-on-unobservables: countries that restructure may have systematically different unobserved growth prospects that simultaneously affect the debt ratio. The authors address one specific form of this concern — that countries and creditors time resolution to coincide with favorable growth — by including 1- and 2-year ahead IMF GDP forecasts as controls in a robustness check, finding similar results. Observations with propensity scores outside [10^-4, 1−10^-4] are excluded to avoid extreme weight instability. Significant overlap between treatment and control propensity score distributions (both approaching full support in [0,1]) is verified.

Why is the timing of restructuring start (vs. end) relevant for the debt ratio?

Prior papers (Reinhart and Trebesch 2016; Cheng et al. 2019) measure the impact from the end of the restructuring episode or the resolution of the debt crisis. This paper instead measures from the start of the restructuring event (the onset of debt crisis). The distinction matters because: (i) the debt stock is only formally reduced at the completion of restructuring (once a deal is struck and recorded), so the numerator of the debt ratio moves discontinuously at the end of the episode; (ii) GDP, however, can be negatively affected from the outset of the crisis, compressing the denominator before any debt relief is delivered. About one-third of restructuring episodes last two or more years, so the distinction is empirically non-trivial. Measuring from the start captures the full dynamic path — including the initial GDP drag and the later debt relief — without conditioning on crisis resolution, which could itself be endogenous.

What does the dataset cover and how does it differ from prior work?

The dataset covers 709 restructuring events in 115 emerging market and developing countries from 1950 to 2021. It includes four creditor classes: private external creditors (sourced from Asonuma and Trebesch 2016), official bilateral external creditors under the Paris Club (from Paris Club database and Horn et al. 2022), official bilateral creditors outside the Paris Club including China (from Horn et al. 2022), and domestic creditors (from IMF 2021). The paper also covers restructurings that occur outside sovereign defaults, including preemptive restructurings where payments are not missed. Prior literature focused primarily on post-default restructurings with external private or Paris Club creditors. The 310 EM restructuring events break down as 85.8% cash flow relief only and 14.2% face value reduction; 58.4% are preemptive, 21.6% post-default, and 20% both or unidentified. For LICs, 396 events are recorded, with 73.5% cash flow relief only and 26.5% face value reduction. Macroeconomic controls come from the IMF WEO October 2022 vintage.

What is the propensity model’s predictive performance, and what does it reveal about the determinants of restructuring?

The first-stage probit achieves an AUROC above 0.85 and a pseudo R-squared of 0.295 on 1,233 observations. Key findings: the lagged treatment dummy is negative and significant (countries that recently restructured are less likely to do so again soon, possibly because creditors resist multiple sequential restructurings); lagged changes in debt-to-GDP are negative in the two years preceding restructuring (reflecting that countries often pursue fiscal consolidation before resorting to restructuring as a last resort); global output gap and GDP growth have the expected signs (restructurings more likely when global conditions are favorable and domestic growth is low), though p-values are near 0.10; US interest rate coefficients have opposite signs for short vs. long rates and are statistically insignificant. The propensity score distributions show significant overlap between treatment and control groups, supporting the common support assumption.

What does the ATE per unit of treatment analysis reveal about cash flow relief vs. face value reduction?

The ATE per unit of treatment is constructed by dividing the estimated ATE by the average size of treatment. For face value reduction events, the size is the average annual face-value-reduction-to-GDP ratio, approximately 6.0 percentage points. For cash flow relief only events (restricted to private external restructurings where present-value data are available from Asonuma et al. 2023), the size is estimated using a back-of-envelope calculation scaling the FVR size by the ratio of present-value debt reduction for cash flow relief (5 percent) to that for FVR (10.6 percent), yielding 2.8 percentage points. Table 4 shows: for FVR, the ATE in year 0 is -10.6 pp (per unit: -1.77), falling to -5.0 pp in year 5 (per unit: -0.83) — a frontloaded and then diminishing profile. For cash flow relief, the ATE is +3.6 pp in year 0 (per unit: +1.29), moving to -5.7 pp in year 5 (per unit: -2.04) — a monotonically increasing profile. The per-unit effects converge by around year 4, supporting the conclusion that treatment depth rather than treatment type is what determines long-run effectiveness.

How is the interaction between restructuring and fiscal consolidation defined and what does the heterogeneity analysis show?

Fiscal consolidation is defined as a positive average cyclically adjusted primary balance during the duration of the restructuring episode. The AIPW model is re-estimated using only the subset of restructuring events meeting this criterion as the treatment group, while keeping all non-restructuring observations as the control group. The estimated ATE ranges from 4.7 percentage points in year 1 to 11.9 percentage points in year 5 — substantially exceeding the 3.8 and 7.2 pp average effects. The long-run amplification relative to the average is larger than the short-run amplification, underscoring that sustained fiscal effort is the dominant factor in durable debt ratio reduction. A robustness check using a weaker definition of fiscal consolidation (positive year-on-year change in the cyclically adjusted primary balance, which can still leave the primary balance negative) shows a larger initial impact but a declining cumulative effect after a few years, consistent with the interpretation that only episodes maintaining a positive (not just improving) fiscal stance sustain the gain.

What does the heterogeneity analysis show for creditor coordination (HIPC/MDRI) versus the average?

Restricting the treatment group to restructuring events under the Heavily Indebted Poor Country Initiative and the Multilateral Debt Relief Initiative, the paper finds ATEs of 5.4 percentage points in year 1 and 6.4 percentage points in year 5. Both exceed the average effects (3.8 and 7.2 pp, respectively) in year 1, though the five-year effect is slightly smaller than the average (6.4 vs. 7.2 pp). The authors contrast this with Easterly (2002), who argued that HIPC countries remained heavily indebted even after two decades of debt relief and concessional financing (1980–1997). The paper’s result suggests that more comprehensive HIPC/MDRI programs produce meaningful and durable reductions in the debt ratio, at least within the five-year window studied.

What does the analysis imply about GDP dynamics during restructuring?

The paper establishes that debt levels fall more in percentage terms than the debt ratio does. In the baseline, the average debt-to-GDP ratio falls 3.8 pp in year 1 while the debt level falls about 7 percent in year 1. A back-of-the-envelope calculation (holding the average debt ratio at roughly 1, so the ratio change approximately equals the percent change in debt minus the percent change in GDP) implies that GDP falls by roughly 3.8 percent after one year of restructuring relative to the year prior, after controlling for selection. Over five years, the debt level falls over 35 percent while the debt ratio falls 7.2 pp, implying cumulative GDP losses that moderate the ratio improvement. The authors confirm this via a robustness check using GDP forecasts as additional controls, finding similar results to the baseline.

What robustness checks are performed and what do they show?

Six main robustness checks are reported: (1) Extending the horizon from 5 to 10 years — effects remain negative throughout, though standard errors widen due to smaller samples. (2) Using the change in debt level (percent) as the outcome instead of the change in the debt ratio — the restructuring reduces debt by about 7 percent on impact and over 35 percent after 5 years, confirming the ratio result is not purely a GDP-denominator artifact. (3) Including 1- and 2-year ahead IMF GDP forecasts as additional controls — results are similar to baseline. (4) Removing interaction terms between the treatment dummy and covariates from equation (1) — results are similar to baseline. (5) Comparing AIPW ATE to a plain OLS local projection (setting the ATE equal to the coefficient on the treatment dummy, without AIPW weighting) — the AIPW attenuates the estimated impact compared to OLS, as expected given upward selection bias: countries in worse shape are more likely to restructure, so naive estimates understate the baseline counterfactual. (6) Alternative probit subsetting for FVR events: removing top/bottom 10% of FVR-to-GDP from the treatment group (to address outliers) produces robust results; alternatively, using the predicted probability of FVR occurrence (based on pre-restructuring information only) to define treatment group membership yields similar findings.

How does this paper relate to and differ from prior work on debt restructuring and debt ratios?

The closest prior papers are Reinhart and Trebesch (2016) and Cheng et al. (2019). Reinhart and Trebesch compare simple pre/post means across 18 AEs (1920–1939) and 35 EMs (1978–2010) — limited by small samples, no causal identification, focus on private external creditors, and measurement from the end of the restructuring episode. Cheng et al. study 93 EMs and LICs (1956–2015) using local projections but cover only Paris Club official creditors and focus on the end of the crisis. The present paper adds: coverage of 115 countries over 1950–2021; a broader set of creditors (private, Paris Club, China, domestic); timing from the start rather than the end of the episode; causal identification via AIPW; and heterogeneity analysis across fiscal consolidation, face value reduction, creditor coordination, and treatment size. The finding that cash flow relief per unit of treatment converges to face value reduction in the long run is novel; prior literature mostly emphasized nominal haircuts. The positive result for HIPC/MDRI also directly contradicts Easterly (2002).

What are the policy implications and their scope conditions?

The key policy implication is that debt restructuring is an effective tool for reducing debt ratios in EMEs and LICs — this is not automatic or mechanical, as GDP effects partially offset the debt stock relief, yet the net effect on the ratio is statistically significant and long-lasting. Scope conditions: (i) The results apply to emerging market economies and low-income countries; advanced economies rarely restructure and the three AE episodes in the sample are excluded as structurally different. (ii) The effectiveness is substantially amplified when restructuring is accompanied by sustained fiscal consolidation (positive average cyclically adjusted primary balance), implying that restructuring alone, without accompanying fiscal effort, provides a smaller and less durable reduction. (iii) Face value reduction is more potent in the short run but converges to cash flow relief in the long run (per unit of treatment), suggesting that deep rescheduling without nominal haircuts can be comparably effective as long as it provides sufficient fiscal space. (iv) The HIPC/MDRI creditor coordination framework is associated with larger-than-average impacts. (v) Preemptive restructurings (without outright default) are included and common, suggesting the results are not limited to post-default episodes. The paper informs current IMF and policymaker discussions on how to manage the post-COVID sovereign debt overhang.

What stylized facts characterize the types of restructuring in the dataset?

Based on Table 2: among EMs, 85.8% of restructurings involve cash flow relief only (no face value reduction) and 14.2% involve face value reduction; 58.4% are preemptive, 21.6% post-default. The most common creditor type in EMs is private external (54.8%), followed by Paris Club (48.1%). Among LICs, 73.5% involve cash flow relief only and 26.5% face value reduction; 54.3% are preemptive and 31.1% post-default; Paris Club is dominant (73.5%). Domestic debt restructurings are rare across both groups; when they occur, they tend to involve smaller face value reductions than external restructurings. The paper also notes that 60% of restructuring events are preceded by an increase in the primary-balance-to-GDP ratio, indicating fiscal effort before crisis resolution is common.

Key Concepts

Augmented Inverse Probability Weighted (AIPW) Estimator: A two-stage causal estimator that first models the propensity score (probability of treatment) and then uses it to re-weight observed outcomes in a local projection, with an augmentation term from the predicted outcome model. It is doubly robust: the average treatment effect is consistently estimated if either the propensity model or the outcome model is correctly specified, but not necessarily both.

Face Value Reduction (FVR): A cut in the nominal (principal) amount of the outstanding debt instruments, also called a nominal haircut. In the paper, the average FVR-to-GDP ratio during restructuring events with FVR is approximately 6 percent per year. FVR events constitute 14.2% of EM restructurings and 26.5% of LIC restructurings in the dataset.

Cash Flow Relief: Debt rescheduling without reduction in face value — encompassing maturity extension and/or coupon rate reduction — that alters the stream of future payments without changing the nominal amount owed. This is the predominant form of restructuring (85.8% of EM events). The present-value size of treatment for cash flow relief is estimated at 2.8 pp of GDP for private external restructurings.

Average Treatment Effect (ATE) per Unit of Treatment: The estimated ATE divided by the average size of the treatment (e.g., face-value-reduction-to-GDP for FVR events, or estimated present-value reduction for cash flow relief events). Used to compare the effectiveness of different restructuring modalities on a common scale, revealing that FVR has a larger per-unit impact in the short run but converges to cash flow relief by year 4–5.

Preemptive Restructuring: A restructuring implemented before any missed payments occur (no legal default), or with only briefly missed payments over a short window after negotiations begin, without a unilateral default. Distinguished from post-default restructurings, which involve unilateral cessation of payments prior to any creditor agreement. Preemptive restructurings account for 58.4% of EM events and 54.3% of LIC events in the dataset.

Doubly Robust Estimator: In the paper’s context, an estimator (the AIPW) whose consistency holds as long as at least one of its two component models — the propensity score model (first stage) or the outcome model (second stage) — is correctly specified. This provides a safeguard against misspecification in one stage, unlike single-model approaches such as simple IPW or plain OLS local projections.

HIPC/MDRI Creditor Coordination: The Heavily Indebted Poor Country Initiative and the Multilateral Debt Relief Initiative, which provide structured large-scale debt relief programs with coordinated participation by multiple official creditors. In the paper, restructuring events under HIPC/MDRI constitute a treatment subgroup showing ATEs of 5.4 pp (year 1) and 6.4 pp (year 5), exceeding the average year-1 effect but roughly in line with the average year-5 effect.