Mississippi Administrative Code
Title 35 - Department of Revenue
Part 3 - Income and Franchise
Subpart 11 - Withholding
Chapter 17 - Registration of Employers
Section 35-3-11-17-101

The Identification Number assigned by the Internal Revenue Service for federal income tax withholding purposes is likewise used for state withholding purposes and such number becomes the identification number of the employer. In making application for registration, the employer should indicate his federal I.D. number on his registration application. If a federal I.D. number has not been applied for or assigned, the Mississippi application should not be delayed, but such number should be furnished as soon thereafter as possible.