EIN for a Single Member LLC

When the IRS requires it

A single member LLC must have its own EIN from the moment any one of these is true:

• It has an employee. Employment taxes are filed under the LLC’s EIN, not the owner’s SSN and not an EIN the owner held as a sole proprietor. This has been the rule since 2009.
• It owes an excise tax. Fuel, heavy highway vehicles (Form 2290), wagering, or anything else filed on Form 720. The IRS online application asks four excise questions for exactly this reason.
• It elects corporate taxation. Form 8832 to be taxed as a C corporation, or Form 2553 to be taxed as an S corporation. The election is filed under the LLC’s EIN.
• It adopts a retirement plan such as a solo 401(k), which files under the plan sponsor’s EIN.

The disregarded entity rule, in plain terms

An LLC with one owner and no election is ignored for federal income tax. There is no separate return: the business goes on the owner’s Schedule C, or Schedule E for a rental, under the owner’s SSN. That is the whole of the rule, and it is why the IRS does not insist on an EIN for the income tax side. Everything the LLC does as an employer, and everything a bank does, sits outside that rule.

Why nearly every single member LLC gets one anyway

• The bank. An account titled to the LLC is opened under the LLC’s EIN and its IRS confirmation letter. Almost no bank will open one on the owner’s SSN, and the ones that do are opening a personal account with the LLC’s name on it. The bank account guide lists what each bank asks for.
• Identity. Without an EIN the owner’s SSN is what goes on contracts, vendor forms and marketplace accounts. An EIN is the number you can hand to strangers.
• Separation. The liability shield depends on the LLC being run as its own entity. Its own tax number, its own account and its own paperwork are the evidence.
• The next step is cheaper. Hiring, an S corporation election and a business loan all need the EIN. Getting it at formation means never redoing the bank paperwork.

The case by case version, including the rental property LLC and the LLC with no income, is in does an LLC need an EIN.

Which number goes on the W-9 for a single member LLC

This is the question that trips up most single owners, and the W-9 instructions answer it directly. A disregarded single member LLC enters the owner’s name on line 1, the LLC name on line 2, checks the individual or sole proprietor box, and enters the owner’s SSN in Part I, or the owner’s own EIN if the owner has one as a sole proprietor. The instructions say not to enter the LLC’s EIN. Once the LLC elects to be taxed as a corporation or S corporation, the LLC’s name and the LLC’s EIN go on the form instead. Line by line, with each case, in how to fill out a W-9 as an LLC.

That rule is about the W-9 only. The LLC’s EIN is still the number for the bank, for payroll, and for the state.

What the SS-4 asks a single member LLC

• Lines 8a to 8c. Yes, it is an LLC; one member; and whether it was organized in the United States.
• Line 9a. A disregarded single member LLC checks “Other” and writes “Disregarded entity”, the wording of the December 2025 instructions. An LLC that will elect corporate taxation checks “Corporation” and names the form it will file. The online application asks the same thing as a question about how the LLC will be taxed.
• Line 7. The responsible party is the owner, with the owner’s SSN or ITIN. An LLC owned by another company names an individual who controls it, since the online application no longer accepts an EIN there.
• Line 10. “Started new business” for a new LLC, even when the bank is the immediate reason.
• Line 11. The date the state approved the LLC, not the date you started trading.

The full LLC walkthrough, including the name as the state recorded it and the mistakes that produce a reference number, is in how to apply for an EIN for an LLC, and every line of the form is filled in for a sample LLC in the single-member LLC SS-4 guide.

Husband and wife LLCs

An LLC owned by two spouses in a community property state (Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington and Wisconsin) may choose to be treated as a single member LLC, and the SS-4 is completed as above with one spouse as the responsible party. In every other state a two spouse LLC is a partnership and follows the partnership rules.

Electing S corporation status later

The EIN does not change. Form 2553 is filed under the LLC’s existing EIN within 2 months and 15 days of the start of the tax year the election is to take effect, and the LLC begins filing Form 1120-S and running payroll for the owner. That is the moment the EIN becomes mandatory, so an LLC that expects to elect should have the number from the start. The deadline and the form are in Form 2553 instructions.

Coming from a sole proprietorship

An EIN you held as a sole proprietor belongs to you as an individual and stays with you. The LLC is a new entity and gets its own number; the IRS will not transfer the sole proprietor EIN to it, and since 2009 an LLC with employees must file under its own EIN in any case. Apply once the state has approved the LLC, so the name on the SS-4 matches the certificate.

Quick answers

Does a single member LLC need an EIN?

The IRS requires one only when the LLC has employees, owes excise taxes, or elects to be taxed as a corporation or S corporation. Nearly every single member LLC gets one anyway, because the bank will not open an account in the LLC’s name without it and because it keeps the owner’s SSN off W-9s.

Can I use my SSN for my single member LLC?

For the owner’s own income tax return, yes: a disregarded LLC reports on Schedule C or E under the owner’s SSN. For a business bank account, a payroll account, or an S corporation election, no. Those need the LLC’s own EIN.

Does the LLC’s EIN go on the W-9?

Usually not. The W-9 instructions tell a disregarded single member LLC to enter the owner’s name on line 1 and the owner’s SSN, or the owner’s own EIN if the owner has one as a sole proprietor, in Part I. The LLC’s EIN goes on the W-9 only once the LLC is taxed as a corporation or S corporation.

Do I need a new EIN if I add a second member?

Yes. The LLC becomes a partnership for tax purposes and needs a new EIN, because the taxpayer changed. Hiring an employee or electing S corporation status does not change the EIN once the LLC has one. The full table is in do I need a new EIN.