IL-505-I: Automatic Extension Payment for Individuals Filing Form IL-1040 (2024)
Illinois · Illinois DOR · Used for tax years 2024
Form IL-505-I is an Illinois extension payment voucher for individuals filing Form IL-1040. It includes a worksheet to calculate tentative tax due after withholding, payments, and credits. Illinois automatically grants a six-month filing extension, but this does not extend the ti
Who files this form
File Form IL-505-I only if all three apply:
- You cannot file your Illinois income tax return by the due date.
- You owe tentative tax, as calculated on the Tax Payment Worksheet.
- You pay by paper check or money order.
If worksheet Line 7 is $1 or more, you must pay that amount. If it is less than $1, no payment is due and you should not file this form. Do not file Form IL-505-I if you pay electronically or by credit card.
You do not need to file this form just to receive the automatic six-month filing extension.
When it's due
For tax year 2024, the form states that calendar-year filers receive an automatic six-month filing extension to October 15.
Any tentative tax must be paid by the original due date of the return. The text does not print a calendar date for that original deadline. If paying by check or money order, send Form IL-505-I with your payment by the original due date, or as soon as you realize you owe tentative tax.
An extension gives you more time to file, not more time to pay.
What you'll need
Have these forms and details available, as applicable:
- Form IL-1040 to estimate your income tax and other taxes.
- Illinois withholding amounts, including pass-through withholding reported on Schedule K-1-P or K-1-T.
- Amounts of estimated payments, overpayments credited to 2024, and previous 2024 IL-505-I payments.
- Information needed to estimate your allowable tax credits.
- Your Social Security number and your spouse’s, if applicable, in the order shown on your federal return, plus names, address, and daytime phone number.
- A check or money order if paying by mail.
To pay from a checking or savings account at mytax.illinois.gov, you need your Illinois Personal Identification Number (IL-PIN).
If you file Form IL-1040 after the automatic six-month extension and the IRS grants an additional extension, attach a copy of the federal extension document to your return.
How to file
- Complete the Tax Payment Worksheet. Add Lines 2 through 5, then subtract that total from Line 1.
- Round the result to whole dollars and enter it on Line 7 and Form IL-505-I.
- If paying by mail, complete and return only the bottom payment voucher with your check or money order. Keep the worksheet for your records.
Make your payment payable to Illinois Department of Revenue. Write your Social Security number, tax year, and “IL-505-I” on the payment.
Mail the voucher and payment to:
Illinois Department of Revenue
P.O. Box 19005
Springfield, IL 62794-9005
Electronic payment: Visit mytax.illinois.gov to pay from your checking or savings account. The form also allows credit card and electronic funds transfer payments. Credit card payments carry a convenience fee. Do not submit Form IL-505-I when paying electronically.
Common mistakes
- Treating the filing extension as extra time to pay. Unpaid tax can lead to a late-payment penalty and interest.
- Sending the voucher when no payment is due or when paying electronically. The form says not to file it in those cases.
- Redacting Social Security numbers. This can delay processing.
- Forgetting to claim extension payments. Claim IL-505-I payments on your 2024 Form IL-1040, Line 26.
- Omitting proof of an additional federal extension. If filing after the automatic six-month period under an IRS-granted additional extension, attach the federal extension document to avoid a late-filing penalty.
Questions people ask
Do I need to request the automatic extension?
No. Illinois automatically grants a six-month filing extension. Form IL-505-I is not required to obtain it.
Can I get more than six months to file?
Only if the IRS grants you an additional extension.
Should I attach an explanation for filing during the automatic extension?
No. If you file within the automatic six-month extension period, do not attach anything to explain the delayed filing.
What happens if I pay late?
You will owe a late-payment penalty if you do not pay the tax by the original due date. Interest runs from the day after that due date through the date you pay. The department will bill you for penalties and interest.