Gotta say I agree with OP. Flat tax is the only fair way. I thought we wanted a free market economy but yet will punish the hell out of the achievers. I am not rich but I do well and I hate what I have to pay now. Its no wonder why companies have to move companies out of the country and also choose not to live in the US as their "primary" residence.
I doubt if there is any country which imposes a flat tax rate.
Abkhazia[28] 10%
Albania[29][30][31] 10%
Andorra[32] 10%
Anguilla[33] 3%
Belarus[31] 12%
Belize[34] 25%
Bolivia[31] 13%
Bosnia and Herzegovina[35][36] 10%
Bulgaria[31][37] 10%
East Timor[38] 10%
Estonia[31][39][40][41] 21%
Georgia[31][41][42] 20%
Greenland[43] 37 to 46% (depending on the municipality)
Grenada[44] 30%
Guernsey[31][45] 20%
Guyana[46] 33.33%
Hungary[31] 16%
Jamaica[31] 25%
Jersey[31][47] 20%
Kazakhstan[31][48] 10%
Kyrgyzstan[45][49] 10%
Latvia[31][41] 25%
Lithuania[31][41][50] 15%
Macedonia[31][45][51] 10%
Madagascar[31] 22%
Mauritius[31][45] 15%
Mongolia[52] 10%
Montenegro[31][53] 9%
Nagorno-Karabakh[54] 5%
Poland 19%
Romania[31][41] 16%
Russia[31][41][55] 13%
Saint Helena[56] 25%
Saudi Arabia[31] 2.5% zakat (citizens of GCC countries)
20% income tax (foreigners)
Serbia[31][57] 12%
Seychelles[31] 15%
South Ossetia[58] 12%
Transnistria[59] 10%
Trinidad and Tobago[31] 25%
Turkmenistan[60] 10%
Tuvalu[61] 30%
Ukraine[31][41][62] 15%
