Actually, I was under the impression that income derived from CFDs is indeed taxable in the UK. US citizens can not escape tax, not matter what or where they trade. But as far as UK traders are concerned as far as I know spread betting is the only way to avoid paying tax on earnings, as it comes under gambling.
"The primary consideration when considering CFD's vs Spread Bets is Tax.
--------------------------------------------------------------------------------
Realised Gains from Spread Bets are not subject to Capital Gains Tax. An ancillary benefit then is that your tax returns are simpler - no representations are required. Realised Losses from Spread Bets are not deductible against other Capital Gains."
"The primary consideration when considering CFD's vs Spread Bets is Tax.
--------------------------------------------------------------------------------
Realised Gains from Spread Bets are not subject to Capital Gains Tax. An ancillary benefit then is that your tax returns are simpler - no representations are required. Realised Losses from Spread Bets are not deductible against other Capital Gains."