The taxpayer shall have his taxable income reduced by so much of any amount payable by him to or on behalf of his spouse or former spouse under any order of divorce or judicial separation granted in consequence of proceedings instituted not later than the twenty-first day of March, 1962, or under any written agreement of separation entered into not later than that date, by way of alimony or allowance or maintenance of his spouse or former spouse and any children, as the Commissioner is satisfied has been or will in respect of the year or period of assessment in question be paid out of the taxable income of the taxpayer: Provided that for the purposes of this section any order of divorce or judicial separation (hereinafter referred to as the subsequent order) which in effect supersedes any such first-mentioned order of judicial separation or written agreement of separation and does not vary the amount of alimony, allowance or maintenance payable thereunder, shall not affect the rights which any person may have under this section, and in the case of any such person and the spouse or former spouse of such person the subsequent order shall, for the purposes of this section and the provisions of section 10(1)(u), be deemed to have been granted in consequence of proceedings instituted on or before the said date.

[Section 21 substituted by section 18 of the Income Tax Act, 1995 (Act No. 21 of 1995)]