Illinois State Tax Guide

State tax registration guide for Illinois.

Need to register taxes in another state? Review the State Tax Guide section in our Tax Services Toolkit.

REQUIRED REGISTRATIONS

  • Unemployment Insurance: Illinois Department of Economic Development

  • Income Tax Withholding: Illinois Department of Revenue

 

REQUIRED INFORMATION

  • SIT ID # (format: XX-XXXXXXX)

  • SIT payment frequency

  • SUI ID # (format: XXXXXXX or XXXXXXX-X)

  • Current year SUI rate

 

REGISTERING FOR UNEMPLOYMENT INSURANCE

You can register online by visiting the MyTax website. Click on Registration, then under I Want To, click Register a new business. Follow the prompts and enter all applicable business information. Once processed, you'll be issued an Unemployment Account number in the format of 1234567-8. The last digit is called the check digit and the department will often omit it from correspondence.

Contact

Visit here for contact information:  top bar Contact, Contact IDES.

Once registered, you will receive an Unemployment Account Number (UI) and Unemployment Rate (%) which you will need to enter into Namely Payroll under Company > Tax screen (UI tax). 

For additional information on registering for taxes, read Employment Tax Registration Overview.

 

REGISTERING FOR INCOME TAX WITHHOLDING  

Registering for a MyTax Illinois Account

  1. Go to https://mytax.illinois.gov/_/.

  2. Click Sign up Now!.

  3. Enter all required business and contact information for your company.

    • Note: Do not use any Namely information for this part of the registration.

  4. Click Submit and answer OK. The IDOR will send a message to the email address you provided with an authorization code required for your initial login.

For assistance with your account, contacts at the Department of Revenue can be found here, navigate to top bar Contact, Contact IDOR.

To activate your MyTax account:

  1. Go to https://mytax.illinois.gov/_/.

  2. Log in using the Username and Password you created in Step 3.

  3. Enter your authorization code. Note: Please be sure to retain the Username, Password, and Security Questions & Answers for your records, as they are required for logging into the MyTax website.

 

Allowing Namely Third-Party Access

You do not need to give Namely TPA to file and pay on your behalf. TPA is however needed for tax notice resolution. Follow the steps below to give Namely access.

  1. Go to https://mytax.illinois.gov/_/.

  2. Log in; Settings.

  3. Select Manage Additional Logons. Make sure the Allow setting under Accountants or Third Party Logons is set to Yes.

  4. Inform your contact at Namely that this has been completed. Namely will request access to your IL SIT account.

  5. After receiving an “access request” email, follow the instructions to allow Namely third-party access.

If you need clarification on these instructions, please visit the Illinois Department of Revenue’s Authentication Guide website, http://tax.illinois.gov/MyTax/AuthenticationGuide.htm.
 

Registering for State Withholding Tax

You can register online by visiting the MyTax website. Click on Registration, then under I Want To, click Register a new business. Follow the prompts and enter all applicable business information. If you haven't yet received your Federal EIN you'll be issued a temporary Illinois Withholding Account Number. If you already have your Federal EIN you'll be able to register using it. Namely Payroll will automatically populate your Illinois Taxpayer ID with your Federal EIN after you finish the Federal Tax Setup step.

Future-date registration is possible for this state's income tax withholding!

Once registered, you will receive a Withholding Tax Account Number (WH) which you will need to enter into Namely Payroll under Company > Tax screen (WH tax).  

For additional information on registering for taxes, read Employment Tax Registration Overview.

POWER OF ATTORNEY FORMS

Please note, Namely does not require a Power of Attorney for this state at this time. It is not required to file or remit payments on your behalf. If one is needed to resolve a tax matter, the tax notice team will request one from you at that time.

If a Power of Attorney is requested from you, you should email completed copies of the forms namelyPOA@Namely.com with the CID in the subject line for processing. We will update our system and maintain a copy of each form for record-keeping purposes

For additional information on Power of Attorney, read Completing the Power of Attorney Package.

 

STATE INCOME WITHHOLDING FORMS

Namely uploads Federal and State W-4 documents to your HRIS site for use during Onboarding, or if you need to send W-4s to employees who need to make withholding adjustments. 

Tip:

The most up to date W-4 documents can be found in the Namely section of the Document dropdown menu in Onboarding and Manage eSignature. 

Form Name: IL-W-4

Accepts Federal W-4: No

Comments: Each employee must provide the employer with a signed Form IL-W-4, Employee's Illinois Withholding Exemption Certificate, to indicate the number of exemptions claimed for state withholding purposes. The withholding certificate takes effect the first payroll period ending, or the first payment of wages after, the date the employee provides the form and remains in effect until the worker provides another certificate. An amended certificate is effective for the first wage payment made on or after the first status determination date (Jan. 1, May 1, July 1 and Oct. 1) unless the employer implements the changes at an earlier date. An employer that does not have a Form IL-W-4 from an employee must withhold on the basis of zero exemptions.

 

PAYROLL + TAX FACTS

Refer to this document for more information: 2022-2023 Federal and State: Payroll and Tax Fact Sheet.