Follow the steps to successfully fill out the IL RUT-25-X online.

1. Click the ‘Get Form’ button to obtain the form and access it in the online interface.
2. Identify the return you are amending and provide the purchaser's details. Enter the original return number, the purchaser's name, their Illinois address at the time the vehicle was brought into Illinois, and their Social Security number or employer identification number if applicable.
3. Mark the reason for filing an amended return by selecting the appropriate checkbox. If the purchase date, the date brought into Illinois, or vehicle description is incorrect, or if there were computational errors, ensure to specify these reasons.
4. If any financial information is changing, complete this section carefully. Round amounts to the nearest whole dollar and attach a copy of the bill of sale, if necessary. Fill out the specified columns to show both the most recent figures filed and the figures that should have been filed, ensuring to follow the instructions for each line.
5. Sign the return under penalties of perjury, indicating that the information provided is accurate to the best of your knowledge. Include the date and have any co-owner sign as well.
6. Complete the payment section as detailed, entering the amount being paid. Ensure your check is made payable to the 'Illinois Department of Revenue' before mailing.

Complete your IL RUT-25-X form online today for a streamlined filing experience.