EIN Guide for a Maine LLP

An Employer Identification Number is a nine-digit federal tax identification number issued by the Internal Revenue Service. It functions like a Social Security number for a business — it's how the IRS, banks, and other institutions identify your partnership. It's sometimes called a federal tax ID or a FEIN, but they all refer to the same number.

Why an LLP always needs one

Unlike a single-member LLC, which can sometimes use its owner's Social Security number, a limited liability partnership always needs its own EIN. The reason is structural: an LLP has at least two partners and is taxed as a partnership by default, which means it files a federal partnership return (Form 1065). That return requires an EIN. You cannot file a partnership return, open a partnership bank account, or run partnership payroll on any individual partner's Social Security number.

What you'll use the EIN for

• Filing the partnership's federal Form 1065 and issuing Schedule K-1s to the partners
• Opening a business bank account in the partnership's name
• Setting up payroll if the LLP hires employees
• Registering with Maine Revenue Services for state tax accounts, such as sales tax
• Providing a tax ID to clients or vendors who need one for their own reporting

Timing matters. Apply for the EIN at the right point in the formation sequence and everything downstream goes smoothly; apply too early or too late and you can create avoidable friction.

Register the LLP first, then get the EIN

The cleanest order is to register your LLP with the Maine Secretary of State first, then apply for the EIN. That way, when the IRS asks for your legal business name and formation details, you're giving it information that already matches the state's record. Applying for an EIN before the partnership legally exists can create a mismatch between the IRS's records and the state's — the kind of small inconsistency that causes headaches when you open a bank account.

Before you open a bank account

You'll need the EIN in hand before most banks will open a business account for the partnership. Since separating partnership finances from personal finances is essential to preserving the liability shield, the EIN is effectively a prerequisite for operating properly. Get it before you start taking in revenue.

The IRS issues EINs at no cost. Be wary of any site that charges a fee just to "obtain" an EIN for you — the number itself is always free directly from the IRS.

Applying online

The fastest route is the IRS EIN Assistant at IRS.gov. The online application is available during the IRS's posted hours, takes about ten minutes, and issues the EIN immediately upon completion. You can download and print the confirmation letter and start using the number the same day.

To apply online, you need a responsible party — generally one of the partners — who has a US Social Security number or Individual Taxpayer Identification Number. The responsible party is the person who ultimately owns or controls the partnership, and the IRS uses this designation to know who's accountable for the entity.

Applying by fax or mail

If no responsible party has an SSN or ITIN, or you simply prefer not to use the online tool, you can apply by submitting Form SS-4 to the IRS by fax or mail. Fax applications typically come back within a few business days; mail applications take longer. This is the usual path for partnerships whose responsible party is a non-US resident without a US tax ID.

What you'll need to have ready

• The LLP's exact legal name as registered in Maine
• The partnership's mailing address
• The name and tax ID of the responsible party
• The reason for applying (started a new business) and the number of partners
• The date the partnership was formed

A few recurring issues catch new partnerships off guard. Knowing them in advance keeps the EIN step simple.

One EIN per entity

Your LLP gets one EIN, and it stays with the partnership. You don't get a new one each year or each tax season. If you registered the partnership and later realize you accidentally applied for two EINs, contact the IRS to have the duplicate closed so your filings all route to a single number.

Don't confuse the EIN with a state tax number

The EIN is federal. If your LLP needs to collect Maine sales tax or has payroll, you'll also register for the relevant Maine state tax accounts through Maine Revenue Services — those are separate identifiers. The EIN often serves as your reference when setting up those state accounts, but it isn't the same thing.

Changing partners usually doesn't require a new EIN

Admitting or removing a partner generally doesn't require a new EIN, because the partnership entity continues. A new EIN is typically needed only in more significant events, such as certain conversions to a different entity type. When in doubt, confirm with your CPA before applying for a second number.

Keep the confirmation letter

The IRS confirmation (the CP 575 notice, or the printout from the online application) is the document banks and agencies ask for to verify your EIN. Store it with your partnership's formation records so it's easy to produce when you open accounts or set up state tax registrations.

One part of the EIN application that partnerships tend to gloss over is the responsible party — and it matters more than it looks.

Who the responsible party is

The IRS requires every EIN application to name a responsible party: a real person who ultimately owns or controls the partnership, not an entity. For an LLP, that's typically one of the partners. The responsible party isn't a mere formality — it's the individual the IRS treats as accountable for the entity, and their tax ID is tied to the EIN in the IRS's records. Only one responsible party is listed, even though an LLP has multiple partners, so decide among yourselves who that will be before you apply.

Keeping the responsible party updated

If the responsible party changes — for instance, the partner originally listed leaves the firm — the IRS expects you to update the record using Form 8822-B. This is easy to forget, because nothing forces the issue day to day, but an out-of-date responsible party can cause confusion if the IRS ever needs to reach the entity. Building this into your partner-transition checklist keeps the record clean.

The EIN survives most partnership changes

Reassuringly, the EIN itself usually stays constant through the ordinary life of the partnership. Admitting or removing partners, changing your address, or moving your registered agent don't require a new number — you update the relevant records but keep the same EIN. A new EIN generally comes into play only in more fundamental events, such as converting to a different type of entity, and even then it's worth confirming the specifics with your CPA before you apply for another one.