A federal tax ID, or Taxpayer Identification Number (TIN), is used by the IRS to administer tax laws. The most common type for businesses is the Employer Identification Number (EIN), a unique nine-digit number. If you are an individual and not operating as a formal business entity with employees, you should generally use your Social Security Number (SSN) for federal tax purposes. If you are not comfortable listing your SSN, you may put zeros in place of it. We will reach out.