| Tax Return Liability Period: 01/01/2017 - 12/31/2017 |
|
|---|---|
| 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 |
