EIM31643 - The general rule for employees: expenses: each and every holder: example
An employee who works in a chemical factory is supplied with protective overalls by their employer. However, they are uncomfortable and restrict their movement and so they buy their own overalls to a design approved by their employer. They ask for a deduction for the cost of replacing and washing their overalls, see EIM32465.
No deduction is due. Protective clothing is necessary but is supplied by the employer. They have bought their own overalls of their own volition and this is not an expense that each and every employee in their employment would need to incur, see EIM31640.