Yes. In almost every case, you need a separate EIN for each LLC you own, because each LLC is its own legal entity and the IRS expects each entity to file under its own nine-digit number.1Internal Revenue Service. Understanding Your EIN (Publication 1635) The one meaningful exception is a single-member LLC with no employees and no excise tax obligations, which can use the owner’s Social Security number for federal income tax reporting instead. Applying is free through the IRS, and the process takes minutes online, so keeping each LLC on its own EIN is mostly a matter of time rather than money.
The Rule: One EIN Per LLC
You should have only one EIN per entity, and one entity should not use another’s number.1Internal Revenue Service. Understanding Your EIN (Publication 1635) Sharing a single EIN across multiple LLCs mixes income, deductions, and payroll in IRS records, which is the kind of mismatch that generates notices. It also weakens the liability separation you set up the multiple LLCs to get in the first place: if the entities look interchangeable on their tax filings, a creditor has an easier argument that they should be treated as one.
The IRS also imposes a practical throttle when you apply. Only one EIN is issued per responsible party per day.2Internal Revenue Service. Get an Employer Identification Number If you are forming several LLCs at once, plan on staggering the applications across business days.
The Single-Member LLC Exception
A single-member LLC is a “disregarded entity” for federal income tax purposes, meaning the IRS looks through the LLC to the owner and reports the activity on the owner’s personal return.3Internal Revenue Service. Single Member Limited Liability Companies If you are the sole owner, you can use your own Social Security number for that income tax reporting, but only if all three of these are true:
- The LLC has no employees.
- The LLC has no excise tax obligations (Forms 720, 730, 2290, or 11-C).
- You have not filed Form 8832 or Form 2553 to be taxed as a corporation or S corporation.
The moment any of those changes, the LLC needs its own EIN. Hiring even one employee is the most common trigger. For employment tax and excise tax purposes, a single-member LLC is treated as a separate entity regardless of its disregarded status for income tax, and it must use its own name and EIN on those returns.3Internal Revenue Service. Single Member Limited Liability Companies
In practice, most single-member LLC owners get an EIN anyway. Banks generally require one to open a business account, and using an EIN keeps your Social Security number off the W-9s and vendor forms you circulate.
Multi-Member LLCs Always Need an EIN
If your LLC has two or more members, an EIN is mandatory. A multi-member LLC defaults to partnership classification for federal tax purposes unless it elects corporate treatment by filing Form 8832.4Internal Revenue Service. LLC Filing as a Corporation or Partnership Either return requires an EIN. A partnership files Form 1065; if the LLC has not yet received a number by the filing deadline, it enters “Applied for” along with the application date.5Internal Revenue Service. Instructions for Form 1065 (2025) – Section: Item D. Employer Identification Number (EIN) An LLC taxed as a corporation files Form 1120 under the same rule.6Internal Revenue Service. Instructions for Form 1120 (2025) – Section: Item B. Employer Identification Number (EIN)
The LLC needs to know its classification before applying, because the classification tells the IRS which returns to expect on the account.7Internal Revenue Service. About Form 8832, Entity Classification Election
Series LLCs
About twenty states allow a series LLC, in which a master LLC creates internal series (sometimes called cells) that each hold their own assets and liabilities. The IRS proposed a regulation in 2010 that would treat each series as a separate entity for federal tax purposes but has never finalized it.8Federal Register. Series LLCs and Cell Companies
Until the IRS issues final guidance, the cautious approach is to give each series that conducts business, holds assets, or has its own tax obligations its own EIN, along with a separate EIN for the master LLC. That approach lines up with the direction of the proposed rule and helps preserve the liability separation between series.
If You Want Fewer EINs, Consider DBAs
If the goal is to run several brands without the administrative weight of multiple entities, a “doing business as” registration is often the simpler path. A DBA is a trade name registered with a state or county, not a separate legal entity. One LLC can operate under multiple DBAs, and all activity flows through the LLC’s single tax return under its one EIN.
The trade-off is liability. Because every DBA is legally the same entity, a lawsuit against one brand reaches the assets behind all of them. Separate LLCs with separate EINs create genuine legal walls between ventures; DBAs give you branding flexibility without asset isolation. Which one fits depends on whether you are protecting distinct pools of assets or just marketing to different audiences.
Does Changing Tax Classification Require a New EIN?
No. If your LLC elects to be taxed as a corporation or S corporation, the same EIN carries over.9Internal Revenue Service. When to Get a New EIN Changing your business name or address does not require a new number either; you update the IRS with Form 8822-B or on your next filed return.10Internal Revenue Service. Address Changes A new EIN comes up in a different set of situations, such as when a single-member LLC that previously used the owner’s SSN hires employees, or when a merger creates a brand-new entity.
How to Apply for Each LLC’s EIN
Applying costs nothing. The IRS is explicit that you should never pay a fee for an EIN and warns about third-party sites that charge for it.2Internal Revenue Service. Get an Employer Identification Number There are three ways to apply:
- Online, which issues the EIN immediately once the application is validated. The tool is available Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturday from 6:00 a.m. to 9:00 p.m., and Sunday from 6:00 p.m. to midnight. Your principal business location must be in the U.S. or a U.S. territory.
- By fax, using Form SS-4. Processing takes about six business days.11Internal Revenue Service. Processing Status for Tax Forms
- By mail, using Form SS-4. Allow about 30 days.11Internal Revenue Service. Processing Status for Tax Forms
Remember the one-application-per-responsible-party-per-day cap.2Internal Revenue Service. Get an Employer Identification Number For five new LLCs, expect a week of applications rather than a single afternoon.
What Happens If You Use the Wrong EIN
Filing information returns with an incorrect or missing taxpayer identification number falls under the general information-return penalty framework, which assesses a per-return penalty.12Office of the Law Revision Counsel. 26 USC 6721 – Failure to File Correct Information Returns For returns due in 2026, the IRS scales the penalty by how quickly the error is corrected:13Internal Revenue Service. Information Return Penalties
- $60 per return if corrected within 30 days.
- $130 per return if corrected after 30 days but by August 1.
- $340 per return if corrected after August 1 or never filed.
- $680 per return for intentional disregard, with no annual cap.
The numbers add up quickly for an LLC issuing dozens of 1099s or W-2s under the wrong number, and the intentional disregard tier removes the annual limit that otherwise caps total exposure. Getting a separate EIN for each LLC before you start filing under it is far cheaper than fixing the returns afterward.