EIM36530 - Deductions from earnings: capital allowances: meaning of 'plant or machinery'
There is no statutory definition of what constitutes ‘plant,’ but most buildings, structures and land are excluded from plant and machinery allowances by statute.
In general, ‘plant’ is apparatus with which the qualifying activity is conducted, if it is kept to use in that activity. Broadly speaking, to qualify as "plant" an item must have a working life of at least two years (see CA21100). For further information, see CA21000.
If an item does not qualify as plant or machinery you will need to consider whether a deduction is due under the general rule for employees’ expenses in Section 336 ITEPA 2003 (see EIM31600 onwards and EIM36510).