CTM98010 - Corporation Tax self-assessment (CTSA): capital allowances: claim must be made in return
Under CTSA, companies must make, amend or withdraw capital allowances claims in their company tax return. If a company has already submitted its return for an accounting period, it can make, amend or withdraw capital allowances claims only by amending its return.
A company may claim less than the full amount available but it must specify the amount claimed.