Section 203(2) ITEPA 2003 covers the general rule for finding the cash equivalent of a benefit. The cash equivalent is:
For the meaning of "made good" see
If a benefit is shared by a number of people, only some of whom are directors or employees, you will have to apportion the expenditure in order to arrive at the taxable benefit (Section 204 ITEPA 2003). There is more about apportionment at EIM21200.