The effectiveness of the tax system can be analysed in various ways. According to the authors one of manifestations of such effectiveness is resistance to tax evasion. This phenomenon is influenced by multiple factors, with few being the level of VAT rates and the number of rates in force in the country concerned. The aim of the considerations is therefore to analyse how the standard VAT rate as well as the number of rates affect the effectiveness of this tax. The research was based on a literature query in the field of value added tax in the European Union. In addition, the problem of tax evasion was indicated and the aggregated data on the size of the tax gap in the Member States were presented. Then, there are the results of the research for 27 European Union countries for 2011–2019. The efficiency of VAT collection was modelled using square function, determining the significance of the parameters of this function, as well as the value of abscissa, which made it possible to group the countries based on how they maintained the efficiency of VAT collection over the analysed period of time. The final part of the study concentrates on the relationship between the efficiency of tax collection and the amount of both the basic rate and the number of rates. The conclusions of the research are as follows: a tax system with a small number of reduced rates, and preferably with one relatively low standard rate, is the system least susceptible to tax fraud. The research also shows a positive correlation between the value of the basic VAT rate along with the number of preferential rates and the scale of the tax gap, i.e., in countries with a higher standard VAT rate and a greater number of preferential rates, the tax gap is greater. The study will enable further investigation into the strategy of determining the optimal VAT rate and the process of its unification. Proposed changes may contribute to increasing the efficiency of VAT administration in EU countries, reducing the shadow economy, tax fraud and positively influencing economic growth.

Great attention has been paid in recent months to high energy prices, including fuel prices. Numerous studies present the threat this poses to economic growth, but history already knows such situations. Therefore, the elementary question was posed: How do fuel prices affect trade and economic growth? The research was based on the Polish economy between 2000 and 2020. Poland is an importer of energy commodities, so it should exhibit strong sensitivity to fuel price changes. A VAR model was created for the Polish economy, including fuel prices, seaborne trade, gross domestic product, and inflation. The results demonstrate that the Polish economy is quite resilient to fuel market turbulence. Obviously enough, it is easier to function in the conditions of lower fuel prices, but high prices are not a reason to panic. Moreover, ongoing technological progress allows economies to weather fuel market crises more easily than was the case back in the 20th century. Therefore, one may unequivocally state that low fuel prices are not a prerequisite for a country’s development. An economy may develop under conditions of higher fuel prices, and panic over high fuel prices only further fuels the inflationary spiral.

The economic activity of businesses and the living standards of the population are largely dependent on inflation. Here, energy prices are of particular importance. Energy is what offers a competitive edge to economies. Therefore, many energy sectors still remain under state control. However, the fuel market is free although highly concentrated. The primary objective of this study was to determine the impact of fuel price changes on inflation in Poland. The research was based on causality models and regression models including asymmetry correction. The flow path was analyzed of price impulses from the basic raw material (i.e., crude oil) through wholesale diesel prices to inflation. The study demonstrates that with each successive stage of raw material processing, price volatility proves to be weaker. However, the final effect is still significant: inflation is largely shaped by energy carriers and, here, specifically by fuel prices. Such results have serious implications for the state’s economic policy. On one hand, they point to the limitations of this policy and, on the other hand, they raise questions about the legitimacy of the reforms that free up energy markets.

The shadow economy weakens fiscal sustainability, hampers the financing of public goods, and impedes the achievement of sustainable development goals. The informal sector remains a persistent challenge for policymakers, as it distorts competition, reduces transparency, and undermines the effectiveness of economic and fiscal policies. The aim of this article is to identify the key factors determining the size of the shadow economy in European Union countries and to provide policy-relevant insights. The analysis covers data on the share of the informal economy in GDP and macroeconomic variables such as GDP per capita, consumer price index, average wages, household consumption, government expenditure, and unemployment, as well as indicators of digital development in society and the economy (DESI, IDT), the share of cashless transactions in GDP, and information on the implementation of digital tax administration tools and restrictions on cash payments. Five hypotheses (H1–H5) are formulated concerning the effects of income growth, labour market conditions, digitalisation, cashless payments, and tax administration tools on the shadow economy. The research question addresses which factors—macroeconomic conditions, economic and social digitalisation, payment structures, and fiscal innovations in tax administration—play the most significant role in determining the size of the shadow economy in EU countries and whether these mechanisms have broader implications for fiscal sustainability and sustainable development. The empirical strategy is based on multilevel models with countries as clusters, complemented by correlation and comparative analyses. The results indicate that the most significant factor in limiting the size of the shadow economy is the level of GDP per capita and its growth, whereas the impact of card payments appears to be superficial, reflecting overall increases in wealth. Higher wages, household consumption, and digital development as measured by the DESI also play an important role. The implementation of digital solutions in tax administration, such as SAF-T or e-PIT/pre-filled forms, along with restrictions on cash transactions, can serve as complementary measures. The findings suggest that sustainable strategies to reduce the shadow economy should combine long-term economic growth with digitalisation and improved tax administration, which may additionally foster the harmonisation of economic systems and support sustainable development.

The formation of crude oil prices and their impact on diesel prices represent a significant economic challenge. The economy’s dependence on energy resources means that the development and competitiveness of the economy, as well as the standard of living of society, are contingent upon energy prices, including those of liquid fuels. It is therefore important to recognise the process by which changes in the price of crude oil affect other commodities. The recognition of these dependencies will have implications for political and fiscal decision-making at the governmental level, investment strategies of enterprises, and patterns of consumption. The research presented in this paper concerns the transmission of crude oil prices and the wholesale and retail prices of diesel oil in Poland between 2010 and 2024. A correlation analysis, a Granger causality test, and an impulse response function calculation were conducted. The research demonstrated that crude oil prices are the cause of the formation of wholesale and retail prices of diesel oil. However, the causality between wholesale and retail prices is bilateral, with a stronger flow of impulses from retail prices to wholesale prices than vice versa. These findings have significant implications for the evolution of the retail market. While the current situation may lead to the monopolisation of the market, it also provides decision-makers with the ability to regulate the market, potentially reducing the volatility of retail prices relative to raw material quotations. Furthermore, it offers a means to safeguard the retail market against speculative activities and mitigate the impact of sudden increases in raw material prices.