How to fix error IL1040-8100-1 ?

ellamariegoulet · ‎April 06, 2026

JohnB5677

You can check several areas that can cause error IL1040-8100-1 to occur.

Check the prior-year Illinois Adjusted Gross Income (AGI),
Double-check the 8-digit IL-PIN,
Be sure the posting of the Driver’s License/State ID details is correct

This will have to match the Illinois Department of Revenue records.

Correct these inputs in the state section,
If issues persist, print and mail your return.

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Mike9241

there is no requirement to enter your DL, just answer you don't have one nor a state ID. The Illinois PIN is the same as used last year, unlike the IRS 5-digit PIN, which you can change every year.

if you filed late, try using $0 for AGI. If you amended, I think Illinois wants the AGI from the amended return, whereas the IRS wants the AGI from the original return if filed timely