To get an EIN for a Mississippi business online, go to IRS.gov and use the free EIN Assistant, which walks you through an interview-style application and issues the nine-digit number on screen as soon as the information is validated.1Internal Revenue Service. Get an Employer Identification Number You’ll then use that number to register for Mississippi state taxes through the Department of Revenue and to open business bank accounts.
Do You Actually Need an EIN
A sole proprietor in Mississippi with no employees who doesn’t file excise tax returns can generally use a personal Social Security number for federal tax purposes. An EIN becomes necessary once any of the following is true:
- You hire employees, even one, and need to withhold and report payroll.
- You operate as a partnership, corporation, or LLC taxed as either.
- You’ll collect Mississippi sales tax or pay federal excise tax; the state uses the federal EIN as its primary identifier.
- You administer a trust, estate, or retirement plan.
- You’re changing business structure or ownership in a way that triggers a new EIN.
Federal regulations require you to apply far enough in advance to have the number before its first required use, meaning before your first tax return, bank account opening, or payroll run.2eCFR. 26 CFR 301.6109-1 – Identifying Numbers
What to Have Ready Before You Start
The online application times out after 15 minutes of inactivity, and you can’t save your progress and come back. Gather everything first:
- The legal name of the entity, exactly as it appears on your formation documents filed with the Mississippi Secretary of State (articles of incorporation, certificate of formation, and so on).3Mississippi Secretary of State. Summary of the Fictitious Business Name Registration Act
- Any trade name you operate under if it differs from the legal name.
- A mailing address (a P.O. box is fine) and a physical street address if different. The IRS does not allow a P.O. box for the physical address.4Internal Revenue Service. Instructions for Form SS-4 (12/2025)
- Your entity type: sole proprietorship, LLC, corporation, partnership, trust, or other.
- Your reason for applying: starting a new business, hiring employees, banking purposes, or another qualifying reason.
- The responsible party’s name and valid Social Security number or Individual Taxpayer Identification Number. This is the individual who controls or manages the entity and its funds.
- Your best estimate of employees over the next 12 months.
One rule catches people forming multiple entities at once: the IRS allows only one EIN per responsible party per day.1Internal Revenue Service. Get an Employer Identification Number Plan the sequence accordingly.
Filing Through the IRS EIN Assistant
To qualify for online filing, your principal place of business must be in the United States, and the responsible party must have a Social Security number or ITIN. Mississippi businesses meet the first requirement by default.
The EIN Assistant is open Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern time, Saturdays from 6:00 a.m. to 9:00 p.m., and Sundays from 6:00 p.m. to midnight.1Internal Revenue Service. Get an Employer Identification Number Instead of filling out Form SS-4 directly, you answer a series of questions covering the information listed above. When the application validates, the system assigns your EIN immediately and lets you download and print the confirmation before you close the session.
Print or save the confirmation before you leave the page. The IRS issues the CP 575 confirmation notice once and will not replace it.1Internal Revenue Service. Get an Employer Identification Number Banks, the Mississippi Department of Revenue, and future business partners commonly ask to see it, so store a digital copy somewhere you’ll find it years from now.
If your principal place of business is outside the United States, the online tool isn’t available to you and you’ll need to call the IRS instead. Mississippi applicants with a U.S. address won’t hit this limit.
Registering for Mississippi State Taxes Next
The federal EIN is step one. Mississippi requires a separate registration with the Department of Revenue before you can collect sales tax, withhold employee income tax, or file corporate income and franchise taxes, and the state uses your federal EIN as the primary identifier during that process.5Mississippi Department of Revenue. Business Tax Frequently Asked Questions
State registration happens through the Mississippi Taxpayer Access Point, known as TAP, on the Department of Revenue’s website. You use TAP to register for sales tax, for a withholding account (required for every employer doing business in Mississippi or paying wages to Mississippi residents), and for corporate income and franchise tax.5Mississippi Department of Revenue. Business Tax Frequently Asked Questions If you’d rather handle corporate income and franchise registration on paper, call the Department of Revenue at (601) 923-7700 to request an application.
Keeping the EIN Record Current
Your EIN never expires, but the information attached to it has to stay accurate. If the responsible party changes, federal regulations require you to notify the IRS within 60 days using Form 8822-B.6Internal Revenue Service. About Form SS-4, Application for Employer Identification Number A new managing member in an LLC, a shift in corporate officers, or a new partner taking over financial control all trigger the requirement.
The same Form 8822-B handles address changes. Missing an IRS notice because it went to an old address doesn’t stop the clock on response deadlines. For information returns filed late or incorrectly in 2026, penalties range from $60 per return if corrected within 30 days up to $340 per return if not filed by August 1, and intentional disregard pushes that to $680.7Internal Revenue Service. Information Return Penalties Those add up with any sizable payroll or contractor list.
Don’t Pay for a Free Service
The IRS does not charge for an EIN. Online, fax, and mail applications are all free.1Internal Revenue Service. Get an Employer Identification Number Dozens of third-party websites charge several hundred dollars to file the same form while presenting themselves as if they were an official government service.
The Federal Trade Commission has flagged the common tactics: mimicking IRS branding with similar seals, logos, and color schemes; putting “IRS” in the domain name; and using the phrase “EIN Assistant,” which is the name the IRS uses for its own free tool. Many of these sites fail to clearly disclose that they aren’t affiliated with the government or that their fee buys something the IRS provides at no cost.8Federal Trade Commission. FTC Warns Operators of Websites That Charge for an Employer Identification Number and Claim Affiliation With the IRS The real application lives at irs.gov. If the URL doesn’t end in .gov, you’re not on the IRS website.