Illinois Form Il 1120 - Enter the amount you are paying. Web if this return is not for calendar year 2023, enter your fiscal tax year here. Due on or before the 15th day of the 3rd month. Small business corporation replacement tax return. Corporation income and replacement tax return:
Small business corporation replacement tax return. Corporation income and replacement tax return: Enter the amount you are paying. Due on or before the 15th day of the 3rd month. Web if this return is not for calendar year 2023, enter your fiscal tax year here.