This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Employment Income Manual

Deductions from earnings: capital allowances: procedures: set-off of excess capital allowances against other income

Section 262 CAA 2001 and Section 128 ITA 2007

If the deductions allowable under the general rule for employees’ expenses in Section 336 ITEPA 2003 exceed the earnings from the employment, no deduction for the excess can be given against other income (see EIM31655).

But if all or part of any capital allowances due cannot be set off against the earnings from the employment, an election can be made for some or all of the excess to be set off against other income (see also EIM32866).

Such claims will be very exceptional and must be referred to an Inspector.