5. For the purposes of regulation 4, the Comptroller may determine —
(a)
the income of an approved global trading company chargeable to the rate of tax in regulation 4(1), (2) or (4), having regard to such expenses, donations and allowances under the Act as are, in the Comptroller’s opinion, to be deducted in ascertaining such income;
(b)
the manner and extent to which any loss arising from the activities specified in regulation 4(1), (2) and (4) may be deducted under the Act in ascertaining such income; and
(c)
the manner and extent to which income attributable to —
(i)
storage in Singapore of the commodities specified for the company; or
(ii)
any activities carried out in Singapore which add value to the commodities specified for the company, by any physical alteration, addition or improvement to them (including refining, blending, processing or bulk‑breaking),
should be excluded from the income mentioned in regulation 4(1), (2) and (4).