§ 22. "That the relief from Surtax given under Section eleven of the Finance (No. 2) Act, 1939, to an individual whose actual earned income is less than his earned income as assessed but is more than four-fifths thereof shall, where the difference between his actual earned income and four-fifths of his earned income as assessed exceeds the relief from standard rate tax to which he would have been entitled under that Section if his actual earned income had been four-fiths of his earned income as assessed, be reduced by the amount of the excess."