Per the IRS website page for Single Member Limited Liability Companies (link here: https://www.irs.gov/businesses/small-businesses-self-employed/single-member-limited-liability-compan...) "For federal income tax purposes, a single-member LLC classified as a disregarded entity generally must use the owner's social security number (SSN) or employer identification number (EIN) for all information returns and reporting related to income tax."
