(b)     domestic or private expenses, including the rent of or cost of repairs of or expenses in connection with any premises not occupied for the purposes of trade or of any dwelling–house or domestic premises except in respect of such part as may be occupied for the purposes of trade: Provided that –

 

(a)     such part shall not be deemed to have been occupied for the purposes of trade, unless such part is specifically equipped for purposes of the taxpayer’s trade and regularly and exclusively used for such purposes; and

 

(b)     no deduction shall in any event be granted where the taxpayer’s trade constitutes any employment or office unless –

 

(i)      his income from such employment or office is derived mainly from commission or other variable payments which are based on the taxpayer’s work performance and his duties are mainly performed otherwise than in an office which is provided to him by his employer; or

 

(ii)     his duties are mainly performed in such part;