Illinois State Income Tax Withholding Information

State Abbreviation:

IL

State Tax Withholding State Code:

17

Acceptable Exemption Form:

IL-W-4

Basis for Withholding:

State Exemptions

Acceptable Exemption Data:

0/Number of Regular Allowances/Number of Additional Exemptions

TSP Deferred:

Yes

Special Coding:

Determine the Total Number of Allowances field as follows:

First Position - Enter 0 (zero).

Second or Third Positions - Enter the number of exemptions claimed.

Determine the Additional Exemptions Claimed field as follows:

First and Second Positions - Enter the number of additional allowances claimed on Line 2 of the IL-W-4. Valid values are 00 through 99. If no allowances are claimed, enter 00.

Additional Information:

None

Additional Resources:

TAXES 15-07, Illinois State Income Tax Withholding

Withholding Formula (Effective Pay Period 06, 2015)

  1. Subtract the nontaxable biweekly Thrift Savings Plan contribution from the gross biweekly wages.
  2. Subtract the nontaxable biweekly Federal Health Benefits Plan payment(s) (includes dental and vision insurance program and Flexible Spending Account - health care and dependent care deductions) from the amount computed in step 1.
  3. Add the taxable biweekly fringe benefits (i.e., taxable life insurance) to the amount computed in step 2 to obtain the adjusted gross biweekly wages.
  4. Multiply the adjusted gross biweekly wages times 26 to obtain the annual wages.
  5. Determine the exemption allowance by applying the following guideline and subtract this amount from the annual wages.

    Exemption Allowance = $2,150 x Number of Exemptions

  6. Determine the additional allowance by applying the following guideline and subtract this amount from step 5 to compute the taxable income.

    Additional Allowance = $1,000 x Number of Additional Exemptions

  7. Multiply annualized taxable wages by 3.75 percent to determine the annual tax.
  8. Divide the annual Illinois tax withholding by 26 to obtain the biweekly Illinois tax withholding.