EIN Guide for Your California LLC

The IRS assigns each business a nine-digit federal tax identification number known as an Employer Identification Number. It functions as a Social Security number for your business — a unique identifier that the IRS, banks, and other institutions use to recognize your LLC.

It's federal, not a California thing

The EIN comes from the IRS and applies to your business everywhere, not just in California. It is separate from anything the California Secretary of State or the Franchise Tax Board issues. Your California LLC gets its state existence from filing the Articles of Organization; it gets its federal tax identity from the EIN.

Why nearly every LLC gets one

• Banking: Almost every bank requires an EIN to open a business checking account for an LLC.
• Taxes: Multi-member LLCs must have an EIN to file their partnership return; LLCs that elect corporate treatment need one too.
• Hiring: You need an EIN to run payroll and report employment taxes.
• Privacy: Using an EIN instead of your SSN keeps your Social Security number off vendor forms, applications, and business paperwork.

Whether an EIN is legally required depends on your LLC's structure and activities, but in practice most owners get one regardless.

When it's required

• Multi-member LLCs: A multi-member LLC is taxed as a partnership by default and must file Form 1065, which requires an EIN.
• LLCs with employees: Any LLC that hires employees must have an EIN to handle federal payroll taxes.
• Corporate tax election: If your LLC elects to be taxed as an S-corporation or C-corporation, it needs an EIN.
• Certain excise or specialized taxes: Some federal tax obligations require an EIN.

When it's technically optional

A single-member LLC with no employees, taxed as a disregarded entity, can technically use the owner's Social Security number for federal income tax. But "can" is not "should." Almost every bank still wants an EIN to open the business account, and most advisors recommend getting one anyway to keep your SSN private and to keep the business identity clean.

Applying is free and, for most applicants, fast. The IRS issues EINs at no cost — never pay a third party a fee for the EIN itself, though a formation service may include the application as part of a package.

Apply online (the fastest route)

1. Go to the IRS EIN Assistant at IRS.gov.
2. Select that you are applying for an LLC and answer the questions about members and management.
3. Provide the responsible party's name and Social Security number or ITIN.
4. Submit the application.
5. Receive the EIN immediately — you can download and print the confirmation and use the number the same day.

The online tool operates during IRS business hours and requires the responsible party to have a valid US SSN or ITIN.

If you don't have an SSN or ITIN

Non-US residents and others without an SSN or ITIN cannot use the online tool. Instead, complete Form SS-4 and submit it to the IRS by fax or mail. This takes longer than the instant online process, so plan ahead if you are forming from outside the US.

Timing tip

Wait until your California LLC is actually formed — that is, your Articles of Organization have been accepted — before applying for the EIN. Applying for the EIN tied to an LLC that does not yet legally exist can create mismatches. Form the LLC first, then get the EIN.

The EIN is a federal number, but you will use it across your California business life.

Banking and vendors

Your bank will ask for the EIN along with your filed Articles of Organization when you open the business account. Vendors and clients who need to issue you a 1099 will request it too — you provide the EIN instead of your SSN, keeping your personal number private.

California tax registrations

When you register for a seller's permit with the California Department of Tax and Fee Administration, or set up an employer account with the Employment Development Department, you will typically supply your EIN. The state uses your federal number as part of your business identity.

What the EIN does not replace

Getting an EIN does not satisfy any California obligation. You still file your Articles with the Secretary of State, file the Statement of Information, and pay the franchise tax to the Franchise Tax Board. The EIN is one piece of the puzzle — the federal tax identity — not a substitute for state compliance.

A few practical points come up often.

Do you need a new EIN if things change?

Generally, an LLC keeps the same EIN for its life. Some changes — such as certain conversions to a corporation, or specific ownership changes — can require a new EIN. Adding or removing members of an existing LLC usually does not. When in doubt, check the IRS guidance or ask a tax professional.

What if you lose your EIN?

If you misplace the confirmation, you can find the number on past tax returns, bank paperwork, or by contacting the IRS Business & Specialty Tax Line to have it looked up.

Where we come in

When you form your California LLC through Mainstay Filing, we can obtain the EIN for you as part of the process, so your business is bank-ready right after formation. Because the EIN itself is free from the IRS, any charge reflects handling the application on your behalf, not a cost the government imposes. We handle the filing and the EIN application; we are not a tax firm, so questions about how your LLC should be taxed — disregarded entity, partnership, or an S-corporation election — are best answered by your CPA.