Social Security Number (SSN): Issued by the Social Security Administration
Employer Identification Number (EIN): Federal tax identification number that identifies a business entity
Individual Taxpayer Identification Number (ITIN): Tax processing number only available for certain nonresident and resident aliens, their spouse, and dependents who cannot obtain a Social Security number(SSN). (9-digit number, beginning with the number "9")
If you are a single-member LLC that is disregarded as an entity separate from its owner, enter the owner’s SSN (or EIN, if the owner has one). Do not enter the disregarded entity’s EIN. If the LLC is classified as a corporation or partnership, enter the entity’s EIN.