How to Get an EIN in Illinois

An Employer Identification Number, or EIN, is your business's federal tax ID. If you're starting an LLC, corporation, partnership, or sole proprietorship with employees in Illinois, you'll need one. The good news: it's free, and the online application takes about 15 minutes.

This guide walks you through the entire process, from determining whether you actually need an EIN to receiving your number and using it with the Illinois Department of Revenue.

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What Is an EIN?

An EIN is a nine-digit number assigned by the Internal Revenue Service (IRS) that identifies your business for federal tax purposes. Think of it as your business's Social Security number. It looks like this: 12-3456789.

The IRS uses your EIN to track your federal tax filings, employment taxes, and other business-related tax matters. You'll need it when opening a business bank account, hiring employees, and filing federal tax returns.

Unlike your Social Security number, an EIN is public information. The IRS publishes business EINs in the Federal Register, which is why you may see your EIN appear in public databases once it's issued.

Does Your Illinois Business Need an EIN?

Not every business needs an EIN, but most do. You're required to obtain one if your business falls into any of these categories:

Your business has employees (even one part-time employee)
You've formed an LLC, corporation, or partnership
Your business is a sole proprietorship that plans to hire employees
Your business operates as an S corporation or similar tax-election entity
Your business has a retirement plan or trust account
Your business is a nonprofit organization
You operate a farm business with employees
You're required to file excise, alcohol, tobacco, or firearms taxes

You may also want an EIN even if you're not required to have one. Many sole proprietors without employees still apply for an EIN to keep their personal and business tax information separate. This adds a layer of privacy and simplifies your accounting.

If you have formed an LLC in Illinois, you almost certainly need an EIN, even if you're the only member and have no employees initially. Most banks won't open a business account without one.

Before You Apply: What You'll Need

Gathering the right information before you start the application saves time and prevents errors. Have the following ready:

Your Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN). The responsible person (usually the owner or officer) provides this. This is the individual who will be associated with the EIN.
Your business legal name. Use the exact name as it appears on your Articles of Organization (for LLCs) or Articles of Incorporation (for corporations), or your DBA filing if applicable.
Your business address in Illinois. This should be your physical location where business operations occur, not a P.O. Box. If you don't have a physical location yet, you can use your home address.
Business structure type. Know whether you've formed an LLC, corporation, partnership, sole proprietorship, or another structure.
Expected date of business start or takeover. Have the date when you expect to begin operations or when you purchased an existing business.
Business classification code. The IRS assigns these based on your industry. You can find the appropriate code by searching the IRS website or entering a description of what your business does.
Number of employees you expect to have in the next year. An estimate is fine.

If you're applying on behalf of a business you don't own (such as an accountant or lawyer applying for a client), you'll also need a power of attorney form signed by the business owner.

How to Get an EIN in Illinois (Step-by-Step)

Method 1: Apply Online (Fastest)

Applying online is the quickest way to get an EIN. You'll receive your number immediately, sometimes within minutes.

Step 1: Go to the IRS EIN application page. Visit https://www.irs.gov/ein and look for the "Apply Online" option. The official online application system is at https://sa.www4.irs.gov/modiein/individual/index.html.

Step 2: Read the eligibility requirements. The IRS will confirm that you're eligible to apply online. Most businesses are, but a few types (nonprofit churches, certain agricultural organizations) must apply by mail or phone instead.

Step 3: Enter your business information. Fill in your business legal name, address, structure type, and the responsible person's name and SSN. Be exact with the name, especially if it matches your Articles of Organization exactly.

Step 4: Confirm your responsible person details. The IRS defines the "responsible person" as the individual who owns or exercises overall responsibility for the business. For an LLC, this is usually the owner or manager. For a corporation, it's typically the president or another officer. For a partnership, it's a partner.

Step 5: Select your industry classification. Choose the code that best describes your business. The form provides a dropdown or search function. If you're unsure, search your industry type (e.g., "retail clothing store" or "consulting") and select the closest match.

Step 6: Answer additional questions. The form asks about employee count, reason for applying, and whether you're taking over an existing business. Answer honestly and completely.

Step 7: Review and submit. Check all information for accuracy. Errors in your business name or address will delay future correspondence from the IRS.

Step 8: Receive your EIN immediately. Once submitted, you'll see your EIN on the screen. Write it down immediately or print the confirmation page. The IRS will also email a copy to you.

The entire online process typically takes 10 to 15 minutes.

Method 2: Apply by Phone

If you can't apply online or prefer to speak with someone, you can apply by phone. Have all the information listed in the previous section ready before you call.

Call the IRS at 1-800-829-4933. This line is available Monday through Friday, 7 a.m. to 10 p.m. Eastern Time. Allow extra time during tax season (January through mid-April), when hold times are longer.

The IRS representative will ask the same questions as the online form and assign your EIN on the spot. You'll receive your number verbally and should confirm it in writing. Ask the representative to mail a confirmation letter to your address.

Phone applications typically take 15 to 30 minutes, depending on call volume.

Method 3: Apply by Mail or Fax

Mail and fax applications take longer but work if you can't apply online or by phone.

Step 1: Download Form SS-4. Get the form from IRS.gov by searching for "Form SS-4" or "Application for an Employer Identification Number." You can also call 1-800-829-3676 to have a form mailed to you.

Step 2: Complete the form by hand or type it. Use black ink if completing by hand. Form SS-4 is relatively straightforward, with 21 lines. Most of the fields are self-explanatory, but the IRS provides instructions on a separate sheet.

Step 3: Mail or fax the completed form. For Illinois businesses, mail to the IRS at the address shown on the form instructions, or fax it to the number provided. The form will specify which fax line to use based on your state.

Step 4: Wait for confirmation. The IRS will mail an approval letter with your EIN. This typically takes 4 to 6 weeks from the date you mail the form. If you include a self-addressed, stamped envelope with your application, they may return it faster.

Mail and fax applications are the slowest option but work if you don't have internet access or prefer not to apply online.

What to Do With Your EIN Once You Have It

After you receive your EIN, take these steps to complete the business registration process in Illinois:

Register with the Illinois Department of Revenue. Even though your EIN is federal, you must also register with the state for Illinois income and sales taxes. This is done through MyTax Illinois at tax.illinois.gov. You'll use Form REG-1 (online registration). This is free and takes one to two business days to process online.
Open a business bank account. Take your EIN letter and business formation documents (Articles of Organization or Articles of Incorporation) to your bank and open a business checking and savings account. The bank will need to verify your EIN and business structure.
Apply for sales tax permits if required. If your business sells tangible goods or certain services in Illinois, you'll need a sales tax permit. This is part of your IDOR registration and is issued automatically with Form REG-1 if applicable to your business type.
Obtain any industry-specific licenses. Illinois requires specific licenses for certain businesses such as liquor sales, food service, healthcare, childcare, and skilled trades. Check with your local city or county and with the Illinois Department of Financial and Professional Regulation for your industry.
Keep your EIN letter safe. You'll need to reference it on federal tax forms, employment tax filings, and when adding employees to your payroll system. Scan a copy and store it with your business records.

Tips and Common Mistakes to Avoid

Mistake 1: Using your personal SSN instead of getting an EIN. If your business has employees or is structured as an LLC or corporation, you need an EIN. Using your personal SSN on business tax forms exposes your personal information and complicates your finances. Get an EIN.

Mistake 2: Typing your business name incorrectly. If your EIN is issued under a name that doesn't match your Articles of Organization, future tax correspondence may go to the wrong party or be rejected by banks. Copy your business name exactly as filed with the Illinois Secretary of State.

Mistake 3: Using a P.O. Box as your business address. The IRS requires a street address, not a mailbox. If you don't have a physical location, use your home address or a coworking space address.

Mistake 4: Not registering with Illinois IDOR after getting your EIN. Your federal EIN is separate from state tax registration. You must register with the Illinois Department of Revenue even though it's free and takes just a few minutes online. Without this registration, you may incur penalties.

Mistake 5: Sharing your EIN too loosely. While EINs are public record, don't list your EIN on your website, social media, or business cards. It can lead to fraud or identity theft targeting your business.

Tip 1: Apply for your EIN before you need it. If you're planning to open a business bank account or hire employees, apply for your EIN right away. The online application is fast enough that same-day bank account opening is possible.

Tip 2: Keep the confirmation email or printed page. If you lose your EIN, you can contact the IRS, but having proof from your application is the fastest recovery method.

Tip 3: Choose the correct responsible person. The responsible person is important for future business correspondence. Pick someone who will be available to receive IRS mail and notices.

Timeline and Next Steps

Your timeline to getting an EIN and being fully registered to do business in Illinois depends on your method:

Online application: EIN issued immediately (within minutes). Illinois IDOR registration follows within 1 to 2 business days if completed the same day.
Phone application: EIN assigned during the call. Confirmation letter arrives within 7 to 10 business days.
Mail or fax application: Expect your EIN letter in 4 to 6 weeks.

Once you have your EIN, you're ready to register with Illinois, open a bank account, and begin hiring if your business plan includes employees. If you're structured as an LLC or corporation, you should have already filed your formation documents with the Illinois Secretary of State before applying for your EIN. The EIN comes after business formation, not before.

Federal vs. State: What You Need to Know

Illinois does not issue a separate state business tax ID. The EIN is your federal number, issued by the IRS. However, you must also complete state tax registration with the Illinois Department of Revenue through MyTax Illinois (Form REG-1). This is free and mandatory if your business has employees or is subject to Illinois income or sales tax. The state will use your federal EIN as a reference, so have it ready when you register with IDOR.

Informational Disclaimer

This article is informational and does not constitute legal or tax advice. EIN requirements, processes, and tax obligations vary based on your specific business structure, state of incorporation, industry, and other factors. The information provided is current as of the publication date and reflects general federal requirements; the IRS may update procedures and requirements without notice.

Before applying for an EIN or registering your business in Illinois, consult with a qualified tax professional or attorney licensed to practice in Illinois. They can advise you on whether an EIN is required for your specific situation and ensure you meet all federal and state filing requirements. Your CPA or business formation service can often handle EIN applications and state registrations on your behalf.

For official IRS information and updates, visit https://www.irs.gov/ein. For Illinois-specific tax registration and compliance, see the Illinois Department of Revenue at tax.illinois.gov.