why do we have a social security number
Social Security number The original purpose of this number was to track individuals' accounts within the Social Security program. It has since come to be used as an identifier for individuals within the United States, although rare errors occur where duplicates do exist. As numbers are now assigned by the central issuing office of the SSA, it is unlikely that duplication will ever occur again. A few duplications did occur when prenumbered cards were sent out to regional SSA offices and (originally) Post Offices.
Employer Identification Number The EIN system was created by the IRS in 1974 by Treasury Decision (TD) 7306, 39 Fed. Reg. 9946. The authority for EIN's is derived from 26 USC 6011(b), requiring taxpayer identification for the purpose of payment of employment taxes. The provision was first enacted as part of the revision of the Tax Code in 1954. This authority was broadened in 1961 by 26 USC 6109. An EIN is usually written in the form 00-0000000 whereas a Social Security Number is usually written in the form 000-00-0000 in order to differentiate between the two. There are EIN Decoders on the web that can identify in what state the company registered the EIN.[3][4]