The extent to which a person can rely on individual guidance given to him will depend on many factors. These could include, for example, the degree of formality of the original query and the guidance given, and whether all relevant information was submitted with the request. Individual guidance is usually given in relation to a set of particular circumstances which exist when the guidance is given. If the circumstances later change, for example, because of a change in the circumstances of the person or a change in the underlying rule or other requirement, and the premises upon which individual guidance was given no longer apply, the guidance will cease to be effective.