The information below is from the 1999 version of the Church Handbook of Instructions and is used in accordance with the fair use provisions of the copyright law.
A person who is excommunicated is no longer a member of the Church. Excommunication is the most severe Church disciplinary action. As directed by the Spirit, it may be necessary for:
1. Members who have committed serious transgressions, especially violations of temple covenants (see "Considerations in Church Discipline," pages 103-4).
2. Members who have been disfellowshipped and have not repented and for whom excommunication seems to offer the best hope for reformation.
3. Members whose conduct makes them a serious threat to others and whose Church membership facilitates their access to victims.
4. Church leaders or prominent members whose transgressions significantly impair the good name or moral influence of the Church in the community that is aware of the transgression.
Excommunication is mandatory for murder and almost always required for incest.
A person who is excommunicated does not enjoy any of Church membership. He may not wear temple garments or pay tithes and offerings. He may attend public Church meetings if his conduct is orderly, but his participation in such meetings is limited the same as for disfellowshipped members.