The EIN identifies your company and is used on all federal income tax filings
Identifying your business
A Federal Tax ID Number or Employer Identification Number (EIN), is basically a Social Security Number for a business. The IRS uses it to identify a business, and it must be included on all your business tax filings. Also, banks typically require an EIN in order to open a business bank account. Other companies that you do business with may also require that your business provide an EIN number in order to pay any of your invoices.
If you currently operate your business as a sole proprietorship or general partnership and want to incorporate or form an LLC, you must obtain a new Federal Tax ID Number (EIN) for your business.