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 correctThis 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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ellamariegoulet

Level 1

Question

How to fix error IL1040-8100-1 ?

Forum|Forum|2 months ago
April 6, 2026
1 reply
3 views

No text available

TurboTax Online

JohnB5677

Level 15

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.

**Say "Thanks" by clicking the thumb icon in a post. **Mark the post that answers your question by clicking on "Mark as Best Answer"

Mike9241

Level 15

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

Mike9241