In 1980, there were roughly 545,000 S corporations filing tax returns in the United States. By 2011, that number was well over 4 million. As S corporations become increasingly popular, it is important to recognize that an S election can be inadvertently terminated. Understanding the ways in which an S corporation can lose the election can help avoid the possibility of double taxation. Discussed below are ten ways in which an S corporation can have the S election revoked, many of which deal with trusts since the rules surrounding trusts as shareholders are complex.