Due to the spike in inflation, the implementation of easy monetary and fiscal policies since the pandemic appears to be coming to an end. The shift towards tighter policies raises concerns about debt sustainability in developing countries, particularly due to the challenge of the "original sin" problem. Given these premises, to analyze debt sustainability for emerging countries, this study focuses on foreign exchange revenue capability and employs external debt-creating (imports, reserves and interest payments) and reducing variables (exports, reserve return and net transfers) for 1995-2020. The results of this panel cointegration estimation for 15 EMDE countries are 0.74 and 0.70 for CCEMG and AMG estimators respectively which indicates moderate sustainability as whole sample countries. However, the individual estimators vary widely for each individual country from weak to strong sustainability.

The spectacular surge of Poland's VAT revenues after 2015 prompted a discussion about the role of the tax administration in collecting tax liabilities. Unfortunately, the scarcity of the available data prevents empirical studies from reaching reliable conclusions about the determinants of VAT revenues. Given that, this article presents a wider attempt at identifying the determinants of VAT revenues in the EU Member States. Using panel cointegration methods, several working hypotheses linking VAT gap to income factors, the business cycle, tax carousels, and an effectiveness of the government are evaluated. The results of the research provide evidence that the VAT gap in the EU countries is under a strong influence from variables approximating changes in per capita incomes, the business cycle, and the openness of an economy to intra-EU trade. The latter finding is a sufficient indication that the improvements made to Poland's tax system were both legitimate and effective.

This paper estimates the magnitude of the Baumol-Bowen and Balassa-Samuleson effects in the Polish economy. The purpose of the analysis is to establish to what extent the differential price dynamics in Poland and in the euro area and the real appreciation of PLN against EUR are explained by the differential in respective productivity dynamics. The historical contribution of the Baumol-Bowen effect to Polish inflation rate is estimated at 0.9 − 1.0 percentage points in the short run. According to estimation results, the Balassa-Samuelson effect contributed around 0.9 to 1.0 percentage point per annum to the rate of relative price growth between Poland and the euro area and 1.0 to 1.2 p.p. to real exchange rate appreciation. The long-run effects are of an approximately twice larger magnitude. Sub-sample calculations and productivity trends over the last decade suggest that this impact should be declining. However, its size is still non-negligible for policymakers in the context of euro adoption in Poland.