This study compares the progressivity of the income tax of Quebec and Ontario. After observing the predominance of income taxation in Quebec and Ontario, by way of international and interprovincial comparisons and illustrating the presence of progressivity in both provinces, progressivity indicators are described. Using these indicators, we measured the progressivity of the Quebec and Ontario tax systems for four different family situations and six levels of income. The results show that in certain situations, Quebec's tax system is more progressive while in others, the reverse is true. More specifically, Quebec's tax system is more progressive for changes in income at the lower end of the income scale while in general Ontario's system is more progressive for higher incomes. These results confirm the greater concentration of Ontario's income tax on high-income taxpayers that we have previously illustrated in the study.