Corporations (other than S corporations) who reasonably expect their income and replacement tax liability to be more than $400 must make quarterly estimated payments. Subchapter S corporations who elect to pay Pass-through entity (PTE) tax and who reasonably expect their income, replacement, and PTE tax to be more than $500 must make quarterly estimated payments. Estimated Payments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the tax year. We encourage you to use our online account management program,
MyTax Illinois, to make estimated tax payments.