Rate of Tax and Contribution by Reference to a Notional Income.

For every £1 of the taxable income of a taxpayer deriving a notional income, as specified by section fifty-nine ab, section eighty-six or section one hundred and fifty-eight d of the Assessment Act, the rate of income tax and social services contribution is the rate ascertained by dividing the tax and contribution which would be payable under the First Schedule upon a taxable income equal to his notional income by a number equal to the number of whole pounds in that notional income.