Instructions
If either of your parents is self-employed or owns a business/farm, you will need to provide information about the business or farm's income, assets and liabilities by submitting the 2025-26 Business/Farm Supplement and the 2023 business return.
Submit the 2023 federal tax return for each business (Partnership, S Corporation or C Corporation) as follows:
Tax forms required by type of business
| Business Type | Tax Form | Include |
|---|---|---|
| Partnership | Form 1065 | K-1 schedules and all attachments |
| S Corporation | Form 1120-S | K-1 schedules and all attachments |
| C Corporation | Form 1120 | All schedules and attachments |
When you are finished, upload the forms to the IDOC website.