Quote Wikipedia:

来源: 于 2014-05-13 07:34:39 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次
The most strict conditions for an employee to be eligible are as follows. The employee must:

1) be at least 21 years of age

2) have worked for the employer for at least three of the previous five years, and

3) have received at least $500(I suppose this has been increased to $550 a year) in compensation for the tax year