What if I need to correct or change my business, trust, or estate return?

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If you need to correct or change your return after it has been filed you must file an amended return for the appropriate tax year. The amended returns for businesses, trusts, and estates are:

• Form IL-1120-X, Amended Corporation Income and Replacement Tax Return, for Form IL-1120
• Form IL-1120-ST-X, Amended Small Business Corporation Replacement Tax Return, for Form IL-1120-ST
• Form IL-1065-X, Amended Partnership Replacement Tax Return, for Form IL-1065
• Form IL-1041-X, Amended Fiduciary Income and Replacement Tax Return, for Form IL-1041
• Form IL-990-T-X, Amended Exempt Organization Income and Replacement Tax Return, for Form IL-990-T

Any correction made may cause a recalculation of penalties and interest.

Note: If an amended return claiming a credit or refund is filed within six months of the expiration of the statute of limitations, then for amended returns filed on or after June 25, 2021, the statute of limitations will automatically be extended an additional six months for issuing an assessment of additional tax due.

For more information see our Business Income Tax Returns web page.  

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