Russia, Saudi Arabia, Ukraine, Serbia and the Republic of Abkhazia. Each of these countries use a flat tax system.
Dr. Ben Carson's Biblical tithe plan is essentially a 10% flat tax. Just like in Albania, Kazakhstan, Turkmenistan, Mongolia, and the Republic of Abkhazia.
More countries that have a flat tax system (Wiki page)
Steven Mnuchin Defends Trump’s Reaction to Charlottesville Violence - The statement from the Treasury secretary, who is Jewish, was perhaps the most vociferous defense of the president from within his administration.
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