439Qualifying expenditure
(1)In this Part “qualifying expenditure” means capital expenditure incurred by a person on research and development directly undertaken by him or on his behalf if—
(a)he is carrying on a trade when the expenditure is incurred and the research and development relates to that trade, or
(b)after incurring the expenditure he sets up and commences a trade connected with the research and development.
(2)The same expenditure may not be taken into account as qualifying expenditure in relation to more than one trade.
(3)The trade by reference to which expenditure is qualifying expenditure is referred to in this Part as “the relevant trade” in relation to that expenditure.
(4)If capital expenditure is partly within subsection (1) and partly not, the expenditure is to be apportioned in a just and reasonable manner.
(5)References in this Chapter to research and development related to a trade include—
(a)research and development which may lead to or facilitate an extension of that trade, and
(b)research and development of a medical nature which has a special relation to the welfare of workers employed in that trade.