County economic growth in multi-tiered fiscal systems depends not only on the volume of transfers but also on whether those transfers pass through intermediary governments. This paper separates administrative delegation from fiscal chain redesign in province-managed county reforms in China. We study 1537 counties from 2000 to 2023 and compare D2, which creates direct province–county fiscal accounts, with D1, which delegates administrative authority but keeps the prefectural intermediary. The empirical design uses panel difference-in-differences estimators, synthetic difference-in-differences, double machine learning robustness checks, and exploratory heterogeneity diagnostics. Based on a placebo-corrected lower bound and a cross-estimator upper bound, D2 is associated with a conservative growth range of 0.35 to 1.0 percentage points per year, while the D1 estimate is imprecise. D2 is also associated with higher contemporaneous per capita fiscal expenditure, but the one-year lagged mediator check does not support a fully identified expenditure mechanism. Heterogeneity patterns are consistent with stronger effects in transfer-dependent counties, but they remain exploratory. The outcome is county economic growth, not a composite sustainability index. The results support a focused governance claim. More reliable transfer delivery is consistent with improved local growth capacity, while fiscal, social, and environmental sustainability remain outside the measured outcome space.

Under China’s dual-carbon agenda, a central question is whether the Low-Carbon City (LCC) pilot policy reduces energy intensity, whether this effect can be credibly interpreted as causal, and under which conditions and through which channels it operates. Using a balanced panel of 282 prefecture-level and higher-level cities from 2006 to 2023, this study develops a problem-oriented framework that integrates effect identification, credibility validation, and heterogeneity and mechanism analysis. The average treatment effect is estimated using staggered difference-in-differences, while dynamic effects are identified with interaction-weighted and imputation-based event-study estimators, and selection concerns are further addressed through propensity score matching difference-in-differences and a battery of stability checks. The results show that the LCC pilot policy reduces urban energy intensity, with the baseline estimate implying a decline of about 15–16%, and that the policy effect accumulates over time rather than appearing immediately. This finding remains stable across alternative specifications, placebo tests, and matched-sample estimation. The policy effect is stronger in cities with higher initial energy intensity and higher levels of economic development. Mechanistic evidence indicates that adjustments in fixed asset investment and changes in AI-related resource allocation are two observable channels associated with the decline in energy intensity. By focusing on energy intensity as a process-oriented performance indicator, this study provides more direct evidence on the energy-efficiency consequences of low-carbon urban governance and clarifies the conditional and structural foundations of policy effectiveness.

Multilevel public finance is a social-administrative system in which authority, fiscal resources, information, and implementation responsibilities circulate across government tiers. China’s Province-Managing-County (PMC) reform provides a case for evaluating how governance redesign affects county-recorded fiscal expenditure. We define the system boundary as the province–prefecture–county fiscal governance chain and decompose the reform into administrative power delegation (D1), which changes decision rights, and fiscal direct reporting (D2), which changes fiscal-flow paths. Using a county-level panel of 2219 counties in 31 provinces from 2000 to 2019, we combine generalized synthetic control, Matrix Completion, panel unconditional quantile regression, and spatial diagnostics. The average effect is positive in the preferred gsynth specification and the Matrix Completion benchmark, but the magnitude is model-dependent: 16.7% under gsynth and 8.1% under Matrix Completion, with further sensitivity to latent-factor choices. Reform-type estimates and a common-model CATE equality test suggest stronger estimated effects for D1 than D2, interpreted as institutional heterogeneity rather than causal dominance. Distributional and spatial diagnostics indicate weaker lower-tail effects and geographically uneven absorption. The findings suggest that changing decision rights and fiscal-flow paths can reshape county fiscal system outputs.