(1) In the Income Tax Acts, except where otherwise provided or the context otherwise requires -

"chargeable tax", in relation to an individual for a year of assessment, means the amount of income tax to which that individual is chargeable for that year of assessment under section 15 in respect of his or her total income for that year including, in the case of an individual assessed to tax in accordance with the provisions of section 1017 or 1031C, the total income, if any, of the individual's spouse or civil partner, as the case may be;

"general tax credit", in relation to an individual for a year of assessment, means any relief (other than a credit under section 59) applicable for that year of assessment, not by way of deduction from income, but by way of reduction of or deduction from the chargeable tax or by way of repayment thereof when paid, other than a personal tax credit, and such credit shall be determined by reference to the amount of the reduction, deduction or repayment as the case may be;

"higher rate", in relation to tax, means the rate of tax known by that description and provided for in section 15;

"incapacitated person" shall be construed in accordance with subsection (5);

"income tax payable", in relation to an individual for a year of assessment, means the chargeable tax less the aggregate of the personal tax credits and general tax credits;