The article deals with theoretical and empirical research of the influence of social tax benefits (allowances) on welfare of families with children in Ukraine and worldwide. International comparisons of basic features and requirements that serve to qualify recipients of the social tax allowance such as income threshold; family size and composition (including relationships, number and age of children); amount of tax deduction (social tax allowance); a tax wedge on labour; untaxed income are carried out.
Basic advantages of tax benefits in comparison with direct state aid are generalized in terms of welfare improvement for families with children. Tax benefits are argued to work better as incentives for parents to increase their labour efforts. In addition, they also decrease pressure on working population, lower demand for government expenditures and eliminate problem of "budget freeriders".
Earned income tax credit (EITC) in the USA has been analyzed regarding whether it is effective in targeting social and fiscal issues in this country. The study concluded that EITC assists a wide scope of low-income families with children and thus establishes high income tax progressivity in different brackets in the USA. The special attention was paid to the provisions of EITC and other in-work tax benefits under the system of married couple (joint) tax filing whose introduction is being currently debated in Ukraine with the aim to promote more socially-oriented tax system.
The efficiency of tax benefits for families with children in Ukraine has been challenged within the analysis of legislative provisions of social tax allowance (STA) and estimation of STA influence on the welfare of low-income (poor) families with children. We have found evidence that STA in Ukraine is characterized with restrictions that make a large group of families with children ineligible and thus a conclusion was made that STA discriminates against those who are really in need. Furthermore, insufficient amount of deduction within STA seems inadequate in order to reduce poverty or increase income tax progressivity. Consequently, some recommendations in order to improve STA in Ukraine are suggested.

Keywords: tax benefits, tax social allowance, tax credit, income tax

The article is devoted to assessing the international competitiveness of the corporate profit tax system based on the approach of the US Tax Foundation, which develops International Tax Competitiveness Index of the corporate profit tax (ICI) and takes into account the level of profit tax rates, cost recovery, tax incentives and complexity of tax law.
According to the analysis of the international ranking of OECD countries, Estonia, Latvia, Lithuania, and Hungary had the highest ICIs in 2019-2020. The main factors that have had a positive effect on their competitiveness are the low top marginal income tax rate, unlimited loss carryback and carryforward, no restrictions on the list of assets subject to depreciation, as well as the use of accelerated depreciation, which allows companies to compensate for a larger share of the initial value of assets, LIFO inventory or at least inventory by the weighted average cost method, no Patent Box; no tax credit for R&D, and low corporate profit tax complexity.
The calculation of the ICI for Ukraine, based on the approbation of the methodological approach of the Tax Foundation, found that in 2019-2020 Ukraine with a total score of 55.07 took 24th place out of 35 OECD countries. The author characterizes the main components of Ukrainian corporate profit taxation in terms of their impact on international competitiveness; in addition, ways to increase ICI are substantiated.

Keywords:international tax competitiveness, corporate profit tax, Patent Box

The article is devoted to the analysis of the corporate income tax gap as one of the indicators that characterizes the tax revenues that a country can accumulate accounting for its economic potential. The author summarizes the main theoretical views on the causes of the tax gap and investigates existing methodological approaches to assess the tax gap on corporate income tax in OECD countries.
The article estimates the income tax gap under the OECD Revenue Administration - Gap Analysis Program, which is based on determining potential tax revenues by adjusting the aggregate indicators of the system of national accounts (gross output, mixed income), which, according to the analysis, averaged at 1.4% GDP in the period 2017-2019, which shows a potential for the development of the fiscal space of Ukraine. Upon analysis of the distribution of the tax gap between institutional sectors of the economy, the largest gap in corporate income tax was found in the sector of foreign corporations whose potential tax revenues were estimated as tripled relative to the declared tax revenues accrued in the Consolidated Budget of Ukraine in 2018.
The author conducted a comprehensive analysis of the effectiveness of corporate income tax in Ukraine on the basis of tax efforts and budget efficiency ratios, which revealed significant weaknesses in comparison with similar indicators in other countries.
The main measures aimed at eliminating tax gaps in OECD countries are summed up and recommendations are made for Ukraine.

Keywords:tax gap, corporate income tax, fiscal space, tax effort, budget efficiency