Optimal public deficit and tax-smoothing in the Spanish Economy, 1850-2024

This paper tests the Tax-Smoothing Hypothesis (TSH) in Spain over a 174-year horizon (1850-2024). Using Dynamic OLS (DOLS) and a bivariate VAR framework, we examine the intertemporal relationship between public revenues and expenditures while accounting for structural instability. The results confirm a long-run cointegrating relationship, but with a tax-tilting parameter consistently between 0.85 and 0.91. This deviation reveals a structural “deficit bias”, where Spanish authorities have systematically postponed tax burdens through debt issuance. Multi-structural break analysis demonstrates that the TSH only becomes a robust framework following the institutional modernization of the mid- 20th century; earlier periods, marked by fiscal archaism and borrowing constraints, fail to conform to the model’s normative predictions. Furthermore, the VAR model confirms that while the budget balance responds rationally to expenditure shocks, its magnitude is heavily influenced by institutional shifts. We conclude that this persistent deficit bias is an embedded feature of the Spanish fiscal state, posing significant challenges for long-term sustainability within the Eurozone’s restrictive fiscal framework.