Illinois State Tax Tables

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Tax rate used in calculating Illinois state tax for year 2024

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 and 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

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Subtract the biweekly Thrift Savings Plan contribution from the gross biweekly wages.
Multiply the adjusted gross biweekly wages times 26 to obtain the annual wages.
Determine the exemption allowance by applying the following guideline and subtract this amount from the annual wages.

Exemption Allowance = $2,775 x Number of Exemptions
Determine the additional allowance by applying the following guideline and subtract this amount from step 3 to compute the taxable income.

Additional Allowance = $1,000 x Number of Additional Exemptions
Multiply the taxable income computed in step 4 times 4.95 percent to determine the amount of Illinois tax withholding.
Divide the annual Illinois tax withholding by 26 to obtain the biweekly Illinois tax withholding.