Where an employee is required to travel between two places of
work, in the same employment, in order to carry out the duties of
that employment, the cost of travel is incurred in the performance
of the duties.
The Courts have approved this practice, for example in Taylor v Provan (49TC579). On page 611 Lord Wilberforce commented:
"If a man has to travel from one place of work to another place of work, he may deduct the travelling expenses of this travel, because he is travelling on his work, but not those of travelling from either place of work to his home or vice versa."
Note though that the expenses of travelling between two workplaces are not normally allowable when one of those places is the employee’s home. See EIM32370.
Where an employee has two employments and the duties of those
employments are performed at different places, the cost of
travelling between them is not travel in the performance of the
duties of the employment.
This point is confirmed by the case of Parikh v Sleeman (63TC75), which concerned a doctor who had separate employments at three hospitals. When he was travelling between the hospitals he was not performing the duties of any of them and so no deduction could be given.
There is an exception to this rule for individuals who are directors of two or more companies within a group of companies, see EIM32035.