There are quite a few myths about income tax. The highest top rate was just over 99%, during the war. It remained c90% between the end of the war and the early 70s, when the differential between earned and unearned income was introduced. The much-quoted 98% rate comprised 83% on earned income and a further 15% on unearned income. The top rate was payable on income of c£200k at today's rates.