The paper looks at the influence of the so-called net tax on household income disparities in Poland. The net tax is understood as the difference between personal income tax (PIT) and social security benefits. This theoretical category makes it possible to identify the total redistributive impact of public transfers and PIT, Aksman says. A Central Statistical Office (GUS) study of household budgets in 2004-2007 was the source of data for the empirical research made by the author. She conducted a statistical and econometric analysis using two definitions of the redistributive effect of net tax based on the Gini coefficient as a measure of income disparities. The research shows that disparities increased in the analyzed period in the case of both original incomes and net household incomes. Original incomes increased by 5.50%, while net household incomes grew 9.29%, Aksman says. She adds that net income disparities were markedly smaller than original income disparities due to the redistributive effect of the net tax. The average net tax rate for original income was positive, showing that households received less in the form of social security benefits than they paid in the form of PIT. This means they were net contributors in this area, Aksman concludes.