Every employer required to deduct and withhold Illinois income tax must register with the Department of Revenue. Each registration application of an employer that has been assigned a federal identification number must contain the employer's federal identification number. If an employer has not been issued a federal employer's identification number, the employer must notify the Department within a reasonable time after its federal employer's identification number has been issued.
Ill. Admin. Code tit. 86, § 100.7040
Amended at 32 Ill. Reg. 17492, effective October 24, 2008