Create a Flat Rate Tax across all income including profit from stocks minus any taxes paid dollar for dollar fed burden

Have the same federal flat rate tax rate across all pay incomes including capital gains profits from sale of stocks/dividends paid from any corporation that has been in business for five or more years. (That allows for the venture capital risk at lower rates) After calculation of federal tax owed to federal government based on flat rate multiplied by yearly income, subtract from the federal tax dollar for dollar any tax already paid to any state, county, city, school, MUD district, fed tax on gas and any other fee so that when all said and done, a true percentage of everyone's income has been paid at the same tax rate.