EIM31622 | The general rule for employees: expenses: how to find the advice you need
From HM Revenue & Customs · Employment Income Manual
To check whether a deduction can be made under the general rule for employers’ expenses, you should follow the steps below in order:
Is the employment included in the list in EIM31623? If it is then look at the advice on that employment to find what deductions can be made
Is the expense listed at EIM31624? If it is then look at the advice on that expense to find out whether a deduction can be made
Otherwise, look at the general advice on the operation of the rule beginning at EIM31630