Do I need to make Illinois estimated tax payments in 2025?

Estimate Illinois quarterly tax payments for 2025 or 2026 by entering projected income, withholding, and credits. The tool compares projected liability with expected withholding and suggests whether estimated payments may be needed.

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Estimates use Illinois’s flat tax rate and are not a substitute for official payment calculations.

How this calculation works

  • Estimates Illinois tax liability from projected income.
  • Subtracts expected withholding and credits.
  • Splits the remaining balance into quarterly targets.

Common mistakes and caveats

  • Safe harbor thresholds can change by year.
  • Exact due dates should be confirmed with Illinois guidance.
  • This is an estimate only.

FAQ

Is this the same as federal estimated taxes?

No. This tool focuses on Illinois state tax estimates only. Federal estimates are separate.

Last updated & sources

Last updated January 27, 2026.

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TaxGuide Pro provides free state and federal tax calculators for individuals, freelancers, and small businesses.

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