如果 single member LLC 没有雇员的话,申请时IRS不会给你EIN的。但是你有了EIN后 (比如从 multi member降为 single member LLC, 或以前有过雇员), 原来的EIN 应该也可以用。 IRS 网页上的原话 Taxpayer Identification Number 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 EIN for all information returns and reporting related to income tax. For example, if a disregarded entity LLC that is owned by an individual is required to provide a Form W-9, Request for Taxpayer Identification Number and Certification, the W-9 should provide the owner’s SSN or EIN, not the LLC’s EIN. A single-member LLC that is a disregarded entity that does not have employees and does not have an excise tax liability does not need an EIN. It should use the name and TIN of the single member owner for federal tax purposes. However, if a single-member LLC, whose taxable income and loss will be reported by the single member owner, nevertheless needs an EIN to open a bank account or if state tax law requires the single-member LLC to have a federal EIN, then the LLC can apply for and obtain an EIN.