Your business needs an EIN if:
You have at least one employee.
You file excise or employment taxes.
Your business structure is a corporation or partnership.
Your business withholds taxes for a nonresident alien's non-wage income.
Even if you aren't legally required to have an EIN, you may want one. That's because an EIN lets you separate your business and personal taxes, which can greatly simplify your life.
However, if you plan on filing for tax-exempt status, it is best for your organization to be legally formed before applying for an EIN. Organizations have three years to file a required return or notice before they lose their tax-exempt status. And applying for an EIN starts that three-year countdown.