Getting an EIN for Your Washington LLP

An Employer Identification Number, assigned by the IRS, is the nine-digit number that serves as a business's federal tax ID. Think of it as a Social Security number for your business — the number the federal government uses to identify your partnership on tax filings and other official records.

Why an LLP specifically needs one

A limited liability partnership almost always needs an EIN, and the reason is structural. An LLP has two or more partners and is generally taxed as a partnership, which means it must file a federal partnership information return (Form 1065). That return requires an EIN — there is no way for a multi-partner business to file it on a partner's Social Security number. Unlike a solo sole proprietor who can sometimes get by on an SSN, an LLP needs its own federal number from the start.

What you use the EIN for

• Filing the partnership's federal tax return and issuing Schedule K-1s to the partners
• Opening a business bank account in the LLP's name — banks require the EIN
• Hiring employees and handling payroll tax withholding and deposits
• Registering with the Washington Department of Revenue and setting up state tax accounts
• Applying for business licenses and, where relevant, credit in the partnership's name

Timing matters. You want the EIN early enough to open accounts and register with the state, but there is a logical order that avoids rework.

Register the LLP first

The cleanest sequence is to register your LLP with the Washington Secretary of State first, so the partnership legally exists and has its name locked in, and then apply for the EIN in that exact name. Applying for an EIN before the entity is registered can create a mismatch between the name on the EIN and the name on your state record, which causes friction later at the bank and with the state.

Then get the EIN, then open accounts

Once the LLP is registered and you have the EIN, you have what you need to open the business bank account, register with the Department of Revenue, and set up payroll if you are hiring. Each of those downstream steps asks for the EIN, so getting it in place unblocks everything that follows.

The IRS issues EINs at no cost, and for most applicants the online process is fastest.

Apply online

The IRS EIN Assistant at IRS.gov is the standard route. The application takes roughly ten minutes, and the number is issued immediately at the end — you can download the confirmation letter and start using the EIN the same day. The online tool is available during set hours, so plan to complete it in one sitting; it does not save partway through.

What you will need

• The LLP's exact legal name as registered in Washington, and its principal address
• The name and Social Security number or ITIN of the responsible party — typically a general partner who controls the entity
• The number of partners and basic information about the business activity
• The state where the LLP is registered (Washington) and the date it started

If you can't apply online

The online application requires the responsible party to have a Social Security number or ITIN. A responsible party without either applies using Form SS-4, submitted by fax or mail. That route takes longer — days to weeks depending on the method — so account for the delay if it applies to you.

The application asks you to name a "responsible party," and getting this right avoids problems down the road.

Who the responsible party is

For an LLP, the responsible party is generally a partner who owns or controls the partnership — the person who ultimately directs its funds and assets. It should be a real individual, not the entity itself. The IRS uses the responsible party to have an accountable human contact for the business's federal tax matters.

Common mistakes to avoid

• Applying before the LLP is registered. Get the entity registered in Washington first so the EIN name matches the state record.
• Using paid services that charge for a free filing. The EIN is free directly from the IRS. Some third-party sites charge a fee to obtain a number you can get yourself at no cost. A legitimate filing service may include EIN assistance as part of a broader package, but the EIN itself carries no IRS fee.
• Getting the name wrong. The EIN should be issued in the LLP's exact legal name. A mismatch between the EIN, the bank account, and the state record creates headaches later.
• Losing the confirmation letter. Save the IRS confirmation (the CP 575 issued at application). Banks and agencies frequently ask for it, and getting a replacement later is slower than keeping the original.

New Washington businesses juggle two different identifying numbers, and it helps to keep them straight.

Two numbers, two governments

The EIN is federal — issued by the IRS, used for federal tax filings, bank accounts, and payroll. The UBI (Unified Business Identifier) is Washington's — assigned when you register with the state, and used across Washington agencies to tie together your Secretary of State record, your Department of Revenue account, and other state interactions. They are not interchangeable; you will use both, in different contexts.

Where each one shows up

• When you file the partnership's federal return or open a bank account, you use the EIN.
• When you deal with the Washington Secretary of State, register with the Department of Revenue, or handle B&O tax, you use the UBI.

Mainstay Filing's role

When Mainstay Filing registers your LLP, we handle the Washington Secretary of State filing that produces your UBI, and we can help you get the EIN squared away so your federal and state identifiers are both in place and consistent. Getting these two numbers set up correctly at the start is what makes opening a bank account and registering for taxes go smoothly instead of turning into a round of corrections.