Illinois Mileage Deduction Calculator
Illinois has a flat 4.95% state income tax. The 72.5¢ federal mileage rate is the same everywhere, but combined with your state tax it determines what a mileage deduction is actually worth in Illinois.
2026 mileage deduction
$5,800
8,000 miles × 72.5¢/mi IRS standard rate
Tax impact
Total tax without deduction $18,148
Total tax with deduction $16,544
Estimated tax savings $1,604
The standard mileage rate already bakes in gas, maintenance, insurance, and depreciation — you can't also deduct those separately for the same vehicle. If your actual vehicle costs run higher than the standard rate implies, the actual-expense method (tracking real costs × business-use %) may deduct more, but requires more detailed records.