Capital allowances must be claimed. If there is no claim there are no capital allowances. Most capital allowances are claimed in the tax return. The claims legislation in TMA70/S42 (income tax) and FA98/SCH18/PARA54 - PARA60 (corporation tax) does not apply to capital allowances claimed in a return.
The claims legislation in TMA70/S42 (income tax) and FA98/SCH18/PARA54 - PARA60 (corporation tax) applies to
A capital allowance claim does not need to be for the full amount of the allowance. But the amount claimed must be specified.