Moved from Delaware to Illinois Mid-Year: Which State Tax Returns Do You File?
Answer
Both states want a return, but neither taxes the whole year. Moving from Delaware to Illinois splits the tax year at the date your residency changed: a Delaware part-year return covers everything before it, a Illinois part-year return everything after. Income is assigned by when it was received.
Last verified
A mid-year move splits the tax year in two, and each state taxes its own half. That is a residency question, so the machinery that governs commuters — reciprocity agreements, convenience rules, nonresident withholding — is beside the point here.
What you file
- 1Part-year return · DelawareForm PIT-NON (part-year resident)
File a Delaware part-year return covering the months you lived in Delaware. A part-year resident of Delaware reports the income received while a Delaware resident, plus any Delaware-source income received during the rest of the year, and prorates the deductions and credits to the residency period.
- 2Part-year return · IllinoisForm IL-1040 with Schedule NR
File a Illinois part-year return covering the months you lived in Illinois. A part-year resident of Illinois reports the income received while a Illinois resident, plus any Illinois-source income received during the rest of the year, and prorates the deductions and credits to the residency period.
The two states, side by side
| Delaware | Illinois | |
|---|---|---|
| Taxes wages | Yes — graduated | Yes — flat |
| Reciprocity partners | None | 4 (Form IL-W-5-NR) |
| Convenience rule | Yes — general rule | No |
| Nonresident return | Form PIT-NON | Form IL-1040 with Schedule NR |
| Part-year return | Form PIT-NON (part-year resident) | Form IL-1040 with Schedule NR |
| Credit for other-state tax | Schedule I (Form PIT-RES) | Schedule CR |
| Nonresident safe harbour | None published | 30 days |
| Local income tax | Yes | No |
| Revenue department | Delaware Division of Revenue | Illinois Department of Revenue |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in Illinois and working in Delaware gives:Two part-year returns.
Same two states, different situation
The withholding answer turns on how you are paid and where the work happens, not only on which two states are involved.
- W-2 commuter: Delaware → IllinoisBoth states — credit offsets the double tax
- Remote worker: Delaware → IllinoisHome state only
- 1099 contractor: Delaware → IllinoisHome state, plus the client state if you work there
Other Delaware pairs
Questions people actually ask
I moved from Delaware to Illinois mid-year. Do I have to file in both states?
Both states want a return, but neither taxes the whole year. Moving from Delaware to Illinois splits the tax year at the date your residency changed: a Delaware part-year return covers everything before it, a Illinois part-year return everything after. Income is assigned by when it was received.
How do I split my income between Delaware and Illinois?
By when you received it, measured against the date your domicile actually changed. Income received while you were a Delaware resident belongs on the Delaware return and income received afterwards on the Illinois return, with each state prorating your deductions, exemptions and credits to its own part of the year. Keep evidence of the move date — a lease, a closing statement, a licence issue date.
How current is this?
The Delaware and Illinois rules on this page were last checked against Delaware Division of Revenue and Illinois Department of Revenue on 2026-08-07. We re-check the full grid every December after state legislative sessions close, and re-check the convenience-of-the-employer states quarterly because that is where the rules move fastest.
Sources
Every fact above comes from the revenue department that publishes the rule. We do not cite secondary summaries, and we do not restate a figure we could not find at source.
- Delaware Division of Revenue — individual income taxaccessed 2026-08-07
- Illinois Department of Revenue — individual income taxaccessed 2026-08-07