CG45920 | Companies and Groups of Companies: Groups of companies: Particular Aspects: loss restriction by reference to capital allowances
From HM Revenue & Customs · Capital Gains Manual
TCGA92/S174 (1) - (3)
The capital gains code does not in general make a distinction between assets qualifying for capital allowances and other assets. This is subject to the following special rules.
If an asset qualifying for capital allowances gives rise to a loss on disposal the expenditure on the asset could, in the absence of a further restriction, effectively be relieved twice. The expenditure obtains relief under the relevant capital allowances code, subject to any balancing adjustment on the disposal of the asset. And if none of the capital gains exemptions applies there would be an allowable loss for capital gains purposes. There is a similar problem where expenditure qualifies for a renewals allowance.