Subsection (2) applies for the purposes of calculating any of the following amounts of profits or chargeable gains—
L in a calculation under section 77C(3),
CIF in a calculation under section 77G(7), and
CIF + NIF in a calculation under section 77G(7) when it is condition E in section 77G that is met.
The amount is to be calculated as if for the purposes of making a separate assessment in respect of those profits or chargeable gains on the person on whom the assessment was made.
An officer of Revenue and Customs applying subsection (2) is to make all such allocations and apportionments of receipts, expenses, allowances and deductions taken into account, or made, for the purposes of the actual assessment as appear to the officer to be just and reasonable in the circumstances.