For the purpose of determining the proportion of profits or assets to which company A would be beneficially entitled as mentioned in section 165(2) or 166(2) at any time, “the relevant accounting period” is the accounting period of company B in which that time falls.

If company B is non-UK resident and is not within the charge to corporation tax, the relevant accounting period is to be determined using the assumption in subsection (3).

The assumption is that company B became UK resident (and, therefore, within the charge to corporation tax) at the time it became a 75% subsidiary (as mentioned in section 136) ignoring section 151(4).