The country with the highest income tax rate varies and can change over time. As of 2021, some of the countries with the highest personal income tax rates include Belgium (50%), Germany (47.5%), and Slovenia (50%). On the other hand, some of the countries with the lowest personal income tax rates include the United Arab Emirates (0%), Bahrain (0%), and Qatar (0%). It's important to note that some countries with low or no personal income tax may have other forms of taxes, such as value-added tax or corporate tax, to make up for the revenue shortfall.