EIB on a Paychex invoice typically stands for Employer Identification Box.
This box is used to include your Employer Identification Number (EIN) or Employer ID, which is a unique number assigned by the IRS to identify your business for tax purposes.
In the context of a Paychex invoice, EIB ensures that all employer-related information, such as payroll, tax filings, and other employer-specific data, is properly linked and processed.