Particular occupations: consultants and other professionals
It is perfectly possible for an employee or a director of a company to provide services quite legitimately to that company in a separate capacity. For example, the individual could be carrying on an established business as a solicitor, estate agent, accountant or some sort of consultant whereby services are supplied to the company on terms similar to those given to other customers. In these cases the payment for the services would not be income from an office or employment assessable under Schedule E/chargeable as employment income or subject to Class 1 NICs.
Where an individual uses a service company, see the guidance at ESM3000