EIN Guide for an Idaho Corporation — How to Get Your Federal Tax ID

An Employer Identification Number — also called a Federal Tax Identification Number — is a nine-digit number the IRS assigns to your corporation. It functions as the business equivalent of a Social Security number: it identifies the corporation to the IRS and appears on the corporation's tax filings and financial accounts.

Corporations always need one

Unlike a single-member LLC, which can sometimes get by on the owner's Social Security number, a corporation always needs its own EIN. A corporation is a separate taxpayer that files its own federal return, so it needs its own federal tax ID from the start. There's no version of a properly run corporation that skips the EIN.

What you use it for

• Filing the corporation's federal tax returns (Form 1120 for a C corporation, 1120-S for an S corporation)
• Opening a corporate bank account — banks require the EIN
• Hiring and paying employees, including payroll tax deposits and filings
• Making the S corporation election on Form 2553
• Registering for Idaho state tax accounts, like withholding and sales tax, which reference the EIN
• Applying for business licenses and permits that ask for a federal tax ID

Timing matters. The EIN sits at a specific point in the formation sequence, and getting it in the right order avoids a common snag.

After the Articles, before the bank account

Apply for the EIN after your Articles of Incorporation are filed and the corporation legally exists, and before you try to open a bank account or hire anyone. The IRS application asks for the corporation's legal name and formation details, so the entity should exist first. The bank account, in turn, requires the EIN, so the EIN has to come before that step.

During formation with Mainstay Filing

When Mainstay Filing forms your corporation, the EIN fits naturally into the sequence right after the state files your Articles. You want the number in hand before your first bank appointment, your first hire, or your first tax registration — all of which reference it.

Don't apply too early

Applying before the corporation is officially formed can create a mismatch between the IRS record and the state record. File the Articles first, confirm the corporation exists, then apply for the EIN with the exact legal name on your filing.

The IRS offers several ways to get an EIN, and one of them is clearly best for most applicants.

Online — the fastest route

The IRS EIN Assistant at IRS.gov issues the number immediately. The online application takes about ten minutes, and you can download and print the confirmation to use the same day. This is the right choice for the large majority of applicants.

To apply online you need a responsible party — usually a principal officer or owner — with a valid U.S. Social Security number or ITIN. The online system requires that identifier to verify the responsible party. The IRS also limits each responsible party to one EIN per day.

Fax and mail

If you can't apply online — most commonly because the responsible party doesn't have an SSN or ITIN — you can file Form SS-4 by fax or mail. Fax typically returns the EIN in a few business days; mail takes several weeks. Non-U.S. responsible parties without a U.S. tax ID generally use this route.

What the application asks

• The corporation's legal name exactly as on your Articles of Incorporation
• The state of incorporation (Idaho) and formation date
• The type of entity (corporation) and your tax classification
• The responsible party's name and SSN or ITIN
• The corporation's mailing address and the reason you're applying

Getting the number is the milestone, but a few follow-ups make sure you actually put it to use correctly and keep it safe.

Save the confirmation

When you apply online, download and save the EIN confirmation notice (the CP 575 or its online equivalent) immediately. It's the official record of your number, and banks and agencies sometimes ask to see it. Store it with your corporate records alongside your Articles and bylaws.

Put it to work

• Open your corporate bank account — bring the EIN confirmation and your filed Articles
• Register for Idaho tax accounts with the State Tax Commission if you'll have employees or make taxable sales
• File your S corporation election on Form 2553 if you're going that route, using the EIN
• Set up payroll if you're hiring, since payroll tax filings reference the EIN

Keep it secure

Your EIN identifies the corporation on financial and tax accounts, so treat it with the same care as any sensitive business identifier. You generally won't need a new one for the life of the corporation — the EIN stays with the entity permanently, even through changes in ownership or address.

A few predictable errors trip up new corporations. Knowing them ahead of time keeps the process clean.

Using a paid service that charges for a free number

The EIN is free directly from the IRS. Some third-party sites charge a fee for what the IRS provides at no cost. There's nothing wrong with a formation service handling it as part of a package, but you should never pay a standalone charge to a website just for the number itself.

Name or entity-type mismatches

Apply with the corporation's exact legal name as filed with Idaho, and select corporation as the entity type. A mismatch between the IRS record and your state record can cause headaches when you open accounts or file returns. Slow down and match the details.

Applying before the corporation exists

Wait until your Articles of Incorporation are filed and the corporation legally exists before applying. Applying too early can create a record that doesn't line up with the state. File first, then get the EIN with the confirmed legal name.