EIN Guide for a Mississippi Corporation — What It Is and How to Get One

An Employer Identification Number is a nine-digit tax ID the IRS assigns at the federal level. Think of it as a Social Security number for your business — it identifies the corporation on tax filings, bank applications, payroll accounts, and other official records.

Why a corporation can't skip it

A single-member LLC can sometimes get by on the owner's Social Security number, because the IRS may treat it as a disregarded entity. A corporation is different. It's a separate taxpayer from its owners from the moment it's formed, which means it needs its own tax ID. There's no version of running a Mississippi corporation where you use a personal SSN in place of a corporate EIN.

What you'll use it for

• Filing the corporation's federal tax return (Form 1120, or Form 1120-S for an S-corporation)
• Opening a corporate bank account — banks require the EIN
• Running payroll and filing employment taxes
• Making an S-corporation election with the IRS
• Registering for Mississippi state tax accounts where required

In short, almost nothing operational happens without the EIN. It's one of the first things to obtain after your Articles of Incorporation are accepted.

Timing matters. You want the EIN early enough to open your bank account and set up operations, but the sequence is worth getting right.

Form the corporation first

Apply for the EIN after your Articles of Incorporation are accepted by the Mississippi Secretary of State. The EIN application asks for the corporation's legal name and formation details, so having the entity officially on record first keeps everything consistent. Applying before the corporation exists can create mismatches you'll have to untangle later.

Then apply promptly

Once the corporation is formed, apply right away. The EIN is issued immediately when you apply online, so there's no reason to wait — and you'll need it before you can open the corporate bank account or run payroll. A common order is: file Articles of Incorporation, hold your organizational meeting and adopt bylaws, get the EIN, then open the bank account.

The IRS issues EINs directly, at no cost. Be wary of third-party sites that charge a fee for what the IRS provides free.

The online application

1. Go to the IRS EIN Assistant at IRS.gov. The online application is the fastest route and issues the number immediately on completion.
2. Select the entity type — corporation — and provide the corporation's legal name exactly as it appears on your Articles of Incorporation.
3. Identify the responsible party. This is the person who controls or manages the corporation, identified by their Social Security number or ITIN. For a small corporation, this is usually the president or principal owner.
4. Provide the corporation's address and formation details, including Mississippi as the state of incorporation.
5. Submit and receive the EIN. The number is issued on the spot. Save and print the confirmation notice (the CP 575) — banks and other parties will ask for it.

Hours and format

The online EIN Assistant operates during set hours on business days and must be completed in one session. Have your details ready before you start so you don't time out partway through.

The online application requires the responsible party to have a US Social Security number or ITIN. That's a common sticking point for non-US founders of Mississippi corporations, but it's solvable.

The alternative route

If the responsible party has no SSN or ITIN, you can still get an EIN by filing IRS Form SS-4 by fax or mail rather than online. The processing time is longer than the instant online issuance — plan for it when scheduling your bank account opening and other steps that depend on the EIN. The form asks for the same information as the online application; you're just submitting it through a different channel.

A note on services

Some formation and filing services will obtain the EIN on your behalf as part of setting up the corporation, which can help if the SS-4 route feels cumbersome. Just remember the IRS itself never charges for the EIN — any fee is for the convenience of someone handling the paperwork, not for the number.

Once issued, the EIN stays with your corporation for its life. You generally won't need a new one unless the entity's structure changes fundamentally.

Practical points to remember

• Store the CP 575 confirmation safely. It's the official proof of your EIN, and reissuing it later is a hassle. Keep a copy with your corporate records.
• Use the exact corporate name tied to the EIN on tax filings and bank documents, so records match.
• You usually keep the same EIN through ordinary changes like moving offices, changing officers, or electing S-corporation status. A new EIN is generally only needed for major structural changes.
• Don't confuse the EIN with state tax IDs. Mississippi may issue separate state tax account numbers for income, franchise, or sales tax through the Department of Revenue. The federal EIN and any state numbers are different identifiers used with different agencies.

With the EIN in hand and your Articles of Incorporation filed, your corporation has the two federal-and-state credentials it needs to open a bank account, hire, and file its returns. Mainstay Filing can obtain the EIN as part of forming your corporation so it's ready when you are.