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Possible online services disruption due to Internet related outage

A worldwide technology outage is causing disruption to some State of Illinois online systems.  We are aware of this issue and are diligently working on restoration.

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How far back can I file an amended return to claim an overpayment based on changes to my federal return?

If your federal change decreases your Illinois tax and you want a refund, you must file an amended return (claim for refund) within two years plus 120 days of federal finalization.

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