Tax Return Liability Period: 01/01/2017 - 12/31/2017 |
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Test transmissions will be accepted: | November 20, 2017 |
Production transmissions will be accepted: | January 29, 2018 |
Last date for timely paid IL-1040 returns: | April 17, 2018 |
Last date to transmit timely filed IL-1040 returns: | October 15, 2018 |
Illinois electronic filing system shuts down: | To be determined* |
Retention of acknowledgment file materials: | December 31, 2018 |
Retention of electronic return-related materials for non-paid preparers: | December 31, 2018 |
Retention of electronic return-related materials for paid
preparers: (Including original Forms IL-8453 and attachments) |
3 years |