Getting an EIN for Your Arizona LLP — A Practical Guide

An Employer Identification Number is a nine-digit number the IRS assigns to a business for federal tax purposes. Think of it as a Social Security number for your partnership — the identifier that ties the firm to its federal tax filings, its bank accounts, and its payroll.

Why an LLP always needs one

A limited liability partnership has, by definition, two or more partners. That means it is treated as a partnership for federal tax purposes, and a partnership must have its own EIN. There is no "disregarded entity" shortcut here — that option exists only for a single-owner business, and an LLP is never single-owner. So unlike a solo LLC that might, in narrow circumstances, operate under an owner's Social Security number, an LLP needs its own EIN from the start.

What you'll use it for

• Filing the partnership's federal return. The LLP files Form 1065 and issues Schedule K-1s to the partners, all under the EIN.
• Opening a business bank account. Banks require the EIN to open an account in the partnership's name — and keeping firm finances separate from the partners' personal accounts is part of running the LLP properly.
• Hiring employees. If the firm has staff, the EIN is used for payroll tax withholding and employment tax filings.
• Registering for Arizona tax accounts. Where the firm needs a transaction privilege tax license or other state accounts, the EIN is the federal identifier tying it together.

Timing matters. The smoothest path is to apply for the EIN after your LLP registration is accepted by the Arizona Secretary of State, so the entity information you give the IRS matches an LLP that actually exists in the state's records.

Register first, then get the EIN

Applying after registration keeps the details consistent — the legal name, the structure, and the responsible party all line up with the LLP on file with the state. If you apply for the EIN before the LLP is registered, you can end up with a mismatch between what the IRS has and what Arizona has, which is easy to avoid by simply sequencing it correctly.

Don't wait too long, either

That said, you generally need the EIN before you can open the partnership's bank account or set up payroll, so do not let it linger. Getting the LLP registered and then promptly applying for the EIN is the right rhythm — registration first, EIN right behind it, then banking and tax setup.

The EIN comes from the IRS, not from the state of Arizona. Whatever you do to register your LLP with the Secretary of State is separate from getting the federal number.

The application methods

• Online. The IRS online application is the fastest route. You complete it in one session and receive the EIN immediately at the end. The online tool is available only during the IRS's posted hours, so plan around that if you have a tight deadline.
• By fax or mail. You can submit the application form (Form SS-4) by fax or mail if you prefer or if the online tool is not available to you. These methods take longer — the online session is instant, while fax and mail add processing time.

The responsible party

The IRS application asks for a "responsible party" — a person who controls or manages the LLP, typically one of the partners, along with their taxpayer identification number. This is a real person, not the entity. Decide among the partners who will be listed before you start the application so you are not scrambling for information mid-session.

The cost

There is no federal fee for an EIN. The IRS issues it for free. Some services charge a convenience fee to obtain the number on your behalf, and that can be worth it if you want the whole formation handled in one place, but the number itself carries no charge.

Getting an EIN is straightforward, but a few recurring errors cause delays or confusion for LLPs.

Watch out for these

• Applying before the LLP is registered. This creates a mismatch between IRS and state records. Register with the Secretary of State first, then apply.
• Choosing the wrong entity type on the application. The IRS asks how the business is classified. An LLP is treated as a partnership by default, so select the classification that reflects a multi-partner entity rather than a single-owner one.
• Confusing the EIN with a state number. The EIN is federal. It is not your Arizona transaction privilege tax license number or any state account number. You may need both, but they come from different agencies and serve different purposes.
• Using a partner's Social Security number instead of getting an EIN. Because an LLP always has multiple partners, it needs its own EIN. Do not run the partnership on a partner's personal number.
• Applying for more than one EIN. Your LLP needs one EIN. If you already have one for the partnership, do not apply again — a duplicate creates confusion in the IRS's records.

After you have it

Once you have the EIN, keep it somewhere safe with your formation documents. You will need it every time you open an account, file a return, register for a state tax account, or set up payroll. Treat it as one of the core identifiers of the firm, right alongside your accepted LLP registration.