Illinois Form IL-1040-X — Amended Individual Income Tax Return 2025-2026
How to fill out Illinois Form IL-1040-X to amend a filed IL-1040 — corrected figures, federal-change rules, required attachments, the 3-year refund limit, and where to mail it.
For correcting a state tax return you already filed — the “X” or “amended” version of the standard form.
How to fill out Illinois Form IL-1040-X to amend a filed IL-1040 — corrected figures, federal-change rules, required attachments, the 3-year refund limit, and where to mail it.