Colorado has a flat income tax rate of 4.63%, and one of the lowest statewide sales taxes in the country, at just 2.90%. However, because of numerous additional county and city sales taxes, actual combined rates can be as high as 11.20%. Most capital gains are taxed at the standard income tax rate of 4.63%%, but there is no estate or inheritance tax in Colorado. The state’s average effective property tax rate is 0.49%. Colorado also has one of the lowest gas taxes in the U.S.