How To Apply For An EIN In Illinois For LLCs (Apr. 2026)

Filing your Articles of Organization with the Secretary of State officially creates your Illinois Limited Liability Company (LLC). Once approved, your next step is to acquire your Employer Identification Number (EIN) from the Internal Revenue Service (IRS). This unique nine-digit federal identification number is used for federal tax purposes. It also allows you to hire LLC employees, obtain your required business licenses, and open a dedicated business bank account.

In this article, I will explain why you need an EIN in Illinois and how to obtain one.

EIN In Illinois Overview

An EIN is a unique 9-digit federal identifier issued by the IRS. It’s used to identify your LLC for federal tax and regulatory compliance procedures. It functions as your taxpayer identification number for the IRS and most other financial institutions.

You need an EIN to complete several important operational and financial obligations, including:

• Filing your required returns and paying your local, state, and federal taxes.
• Opening a dedicated business bank account.
• Obtaining your required licenses and permits.
• Hiring LLC employees and completing payroll.

An EIN is free to obtain ($0) if you apply directly through the official IRS website. This can be done online, by mail, or by fax. You should do this immediately after obtaining your approved Articles of Organization formation documents.

1. EIN Synonyms

Your EIN may be referred to by several different names, with each of them meaning the same federal identifier. I’ve listed them in the table below to help prevent confusion when completing your filings.

2. Do You Need An EIN In Illinois?

Your EIN requirements are based on your federal tax classification, unless you’re a foreign LLC owner. In this case, you need an EIN regardless of your tax classification, as it’s the only identifier used to file your tax returns with the IRS.

U.S. residents forming single-member LLCs do not always need an EIN, as they can use a Social Security Number (SSN) to complete their tax filings. On the other hand, multi-member LLCs require an EIN as they’re taxed as partnerships by default, and tax filings of partnerships require an EIN to complete.

In practice, nearly every Illinois LLC must get an EIN due to state-level tax obligations. I’ve broken down the different rules and regulations in the sections below.

How To Get An Illinois EIN For LLCs?

Your application methods are generally the same across all U.S. states. Your U.S. residency status is the main factor determining which methods are available to use.

1. For U.S. Citizens

You can use any available method if you’re a U.S. resident with an SSN or Individual Taxpayer Identification Number (ITIN). However, I strongly recommend using the online filing method as it’s the fastest and easiest option.

Your application should take approximately 15 minutes to complete. Once filed, you should receive your EIN immediately.

You can read my guide on How To Apply For An EIN Online for step-by-step instructions.

2. For Non-U.S. Residents

Non-U.S. residents without an SSN or ITIN can NOT use the online filing method. Therefore, they must complete Form SS-4 and submit it using one of the methods below:

• By fax: 855-215-1627 (within the U.S.) or 304-707-9470 (from outside the U.S.). Your application will be processed in 4 business days.
• By mail: IRS (attn: EIN operation), Cincinnati, OH 45999. This usually takes 4 weeks + mailing time to process.

Check out my guide on How To Get An EIN Using Form SS-4 for a step-by-step walkthrough.

EIN Approval (EIN Confirmation Letter)

The IRS will issue your official EIN Confirmation Letter once your application has been approved. This will include your EIN.

1. How You Will Receive Your EIN Confirmation Letter

Once approved, you’ll receive your EIN Confirmation Letter (Form CP-575) from the IRS. This acts as official proof that your LLC has an EIN for federal tax and employment purposes.

• Your CP-575 Form is available for immediate download if you apply online.
• The IRS will send your EIN Confirmation Letter by mail if you apply by fax or mail.

2. How Can You Find Your EIN Number Online

If you lose your EIN Confirmation Letter or fail to download it after completing your online application, the IRS will NOT re-issue your original EIN Confirmation Letter (Form CP-575).

If this happens, you need to request an EIN Verification Letter (Form 147C) instead. Both forms hold the same legal standing and will be accepted by banks, government agencies, and financial institutions.

• Contact the IRS directly at 800-829-4933 (Monday to Friday, 7 A.M. to 7 P.M. ET).
• The IRS can also provide your EIN over the phone once you’ve verified your identity and business authority.

Is Your Illinois LLC Required To Have An EIN?

If you’re an Illinois LLC, your EIN requirements depend on your federal tax classification. This also determines your state tax treatments.

• The IRS treats single-member LLCs as disregarded entities and multi-member LLCs as partnerships by default.
• LLCs can choose to be taxed as corporations (S-corporations or C-corporations) by filing the right forms with the IRS.

1. Single-Member LLCs Taxed As Disregarded Entities

Single-member LLCs are NOT technically required to get an EIN at the federal level. They can report taxes using their SSN or ITIN. However, this isn’t a good idea, especially when you start operating. You need an EIN to open a dedicated business bank account, hire LLC employees, and run payroll.

Furthermore, you must get an EIN to register with the Illinois Department of Revenue (IDOR) for a tax account ID or license number. I’ve discussed this more in the sections below.

2. Multi-Member LLCs Taxed As Partnerships

You must get an EIN if you’re a multi-member LLC taxed as a partnership by default. This is the only way for the IRS to recognize your LLC as a separate taxpayer. You also need it to complete your federal tax filings and obligations.

This requirement is set out in 26 Code of Federal Regulations (C.F.R) § 301.6109-1(a)(1)(ii)(C).

3. LLCs Taxed As Corporations

You must also get an EIN if you’re an LLC that has elected to be taxed as a corporation. According to 26 C.F.R. § 301.6109-1(a)(1)(ii)(C), you need an EIN to process your corporate tax returns, complete federal tax compliance, and handle payroll reporting.

The Importance Of Getting An EIN For Your Illinois LLC

There are three main reasons why you should get an EIN for your Illinois LLC. I’ve discussed each one in more detail below.

1. Complying With State Requirements

You need to obtain an EIN to complete certain state-level obligations. One of the most important ones is the IDOR’s business registration. Every Illinois LLC conducting business in the state or with Illinois customers must get one.

a. Can You Have Your Illinois Tax ID Without An EIN?

Without an EIN, you can NOT complete the first step of Form REG-1 to register your LLC (shown below as the “FEIN” field marked with a red asterisk). This applies even if your LLC has already completed a filing with the Secretary of State.

b. What Happens If You Operate Without Registration

If you attempt to operate without a valid EIN, you face several layered consequences. Penalties may accrue daily until you complete your required registration. These may include:

• Liability for the unpaid tax.
• Non-filing penalties (even if no tax is due) and non-payment (if any).
• Enforcement actions, including suspension, audits, and business license revocation or denial.

2. Avoid Federal Legal And Tax Compliance Risks

You face major federal compliance risks if you operate your LLC without an EIN. These include taxpayer identification, tax filing and payment, and withholding obligations.

a. Failure To Furnish Required Taxpayer Identification

Under the IRS, you’re considered to be committing a violation if you’re required to file federal tax or information returns but fail to provide a valid EIN.

If you submit Form 1099 to report payments to independent contractors without a valid EIN, you face two penalties. These happen at the same time:

• IRC § 6721 for filing incorrect or incomplete information returns.
• IRC § 6722 for failing to provide accurate payee statements.

These penalties apply on a per-return basis:

• The standard penalties are up to $340 for each one.
• Both penalties can rise to $680 per return or 10% of the required amount if the violation is deemed to be intentional.

b. Failure To File Return And Pay Federal Taxes

Your Illinois LLC can NOT perform several important business functions without a valid EIN:

• File federal income tax returns.
• Issue or receive reportable payments.

These are your potential penalties under IRC § 6651, as informed in the IRS’s Failure to file penalty documents:

• $255 penalty per partner per month: This applies to multi-member LLCs taxed as partnerships by default (2026 returns).
• 5% of the unpaid tax for each month (up to 25%) + additional penalties: This applies to LLCs taxed as corporations (if no tax is due but a return is required).

c. Failure To Comply With Federal Withholding Obligations

Under IRC § 6672, you face potential fines and imprisonment if your LLC has employees and fails to withhold or remit the required employment taxes.

You can only complete this obligation if you have a valid EIN. Without one, your LLC can NOT:

• Report employee withholding amounts.
• Pay the required employment taxes legally.
• Register payroll tax accounts.

3. Operational Risks

Obtaining an EIN ensures that your LLC can operate as a real business within the U.S. financial and tax system. You are forced to use the following identifiers instead if you don’t have one:

• Your personal bank account.
• Your SSN.

This reduces the separation between your personal finances and business assets, weakening your limited liability protection.

When Do You Need To Obtain An EIN For Your LLC?

Under the IRS guidelines, your LLC must legally exist as an independent entity first before it can apply for and obtain an EIN. If you apply too soon, your filing may be delayed or rejected.

Furthermore, make sure you confirm your member number before officially forming your LLC. This determines whether your business will be classified as a single-member LLC or a multi-member LLC. Changes performed after formation may require significant paperwork.

IRS Key Contact Information

You can contact the IRS if you need assistance with EIN-related matters. They can answer general questions regarding your filing, but will NOT provide legal or tax advice.

• Business contact number: 1-800-829-4933.
• Hours: Monday to Friday, 7:00 A.M. – 7:00 P.M. (ET).

Follow the steps below to be connected to a live representative once you’ve connected:

1. Press “1” for English.
2. Press “1” for EIN-related matters.
3. Press “3” if you have an EIN but cannot locate it (this is the only way to reach a live representative).

Frequently Asked Questions