This second edition of the Dictionary of Taxation contains over 200 new or substantially revised entries to enhance the existing wide range of accessible definitions and terms used to describe various aspects of tax and tax systems around the world.
‘wholly, exclusively and necessarily’
The ﬁrst part of the restrictive condition on claiming employment expenses against income taxes in the UK. To qualify, the expenses must be ‘wholly, exclusively and necessarily incurred in the performance of the duties of his employment’. This has been known as the ‘Rule’, and has been enforced very narrowly. In Lomax v. Newton  34 TC at pp.561–2, Vaisey J. stated:
One case which attracted considerable media attention and comment was that of the BBC newsreader who appealed against the disallowance of her claim for professional clothing. It was argued on her behalf that should she wear the same clothes frequently while reading the news on television, she would lose her job. It was claimed she would be willing to read the news naked, but the BBC required her to wear clothes. Her appeal failed since the clothes could be used outside work and therefore the cost of them was not incurred wholly, necessarily and exclusively in the performance of employment duties (Ms Sian Williams v Revenue & Customs  UKfTT 86 (TC).) See also employment expenses .
p. 292I would observe that the provisions of that Rule are notoriously rigid, narrow and restricted in their operation. In order to satisfy the terms of the Rule it must be shown that the expenditure incurred was not only necessarily but wholly and exclusively incurred in the performance of the relevant ofﬁcial duties. And it is certainly not enough merely to assert that a particular payment satisﬁes the requirement of the Rule, without specifying the detailed facts upon which the ﬁnding is based. An expenditure may be “necessary” for the holder of an ofﬁce without being necessary to him in the performance of the duties of that ofﬁce; it may be necessary in the performance of those duties without being exclusively referable to those duties; it may perhaps be both necessary and exclusively, but still not wholly so referable. The words are indeed stringent and exacting; compliance with each and every one of them is obligatory if the beneﬁt of the Rule is to be claimed successfully. They are, to my mind, deceptive words in the sense that when examined they are found to come to nearly nothing at all.