When starting a new business, a company must obtain an EIN/Tax ID number. For tax identification purposes, all business entities must have an EIN. And for its owner to change, a business will have to obtain a new EIN. Furthermore, household employees will need EINs. When opening a bank account or applying for credit, an organization needs an EIN. If you create a trust, a pension plan, a corporation, a partnership, or LLC, you will need an EIN.