1099 Contractor in Illinois with a South Carolina Client: Where Do You File?
Answer
The client's location does not decide this. Self-employment income from personal services is sourced to where the work happens, so working from Illinois keeps it Illinois-source and Illinois-taxed. Travel to South Carolina to work and that portion becomes South Carolina-source, needing a South Carolina nonresident return.
Last verified
The client's location is the wrong thing to track. What matters is where you were sitting when you did the work — which is why a contractor's exposure to South Carolina is measured in days on the ground rather than in invoices sent.
South Carolina publishes no de minimis day count or dollar floor for nonresidents. Any South Carolina-source wage income above the state's general filing threshold requires a nonresident return, and that threshold is reset each year — check the current figure on the South Carolina Department of Revenue nonresident instructions before filing.
What you file
- 1Quarterly estimated payments · Illinois
Make quarterly estimated payments to Illinois Department of Revenue on your full self-employment income — nothing is withheld from a 1099.
- 2Nonresident return · South CarolinaForm SC1040 with Schedule NR
File a South Carolina nonresident return only if you performed services inside South Carolina. South Carolina publishes no de minimis day count or dollar floor for nonresidents. Any South Carolina-source wage income above the state's general filing threshold requires a nonresident return, and that threshold is reset each year — check the current figure on the South Carolina Department of Revenue nonresident instructions before filing.
- 3Resident return · IllinoisSchedule CR
File the Illinois resident return last and claim the credit for any tax paid to South Carolina.
The two states, side by side
| Illinois | South Carolina | |
|---|---|---|
| Taxes wages | Yes — flat | Yes — graduated |
| Reciprocity partners | 4 (Form IL-W-5-NR) | None |
| Convenience rule | No | No |
| Nonresident return | Form IL-1040 with Schedule NR | Form SC1040 with Schedule NR |
| Credit for other-state tax | Schedule CR | Form SC1040TC |
| Nonresident safe harbour | 30 days | None published |
| Local income tax | No | No |
| Revenue department | Illinois Department of Revenue | South Carolina Department of Revenue |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in South Carolina and working in Illinois gives:Home state, plus the client state if you work there.
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: Illinois → South CarolinaBoth states — credit offsets the double tax
- Remote worker: Illinois → South CarolinaHome state only
- Moved mid-year: Illinois → South CarolinaTwo part-year returns
Other Illinois pairs
Questions people actually ask
I live in Illinois and my client is in South Carolina. Do I have to file a South Carolina tax return?
The client's location does not decide this. Self-employment income from personal services is sourced to where the work happens, so working from Illinois keeps it Illinois-source and Illinois-taxed. Travel to South Carolina to work and that portion becomes South Carolina-source, needing a South Carolina nonresident return.
Do reciprocity agreements help a 1099 contractor?
No. Every state reciprocity agreement in the country is an arrangement about wage withholding between two revenue departments, and a 1099 has no withholding to switch off. Whether Illinois and South Carolina hold an agreement makes no difference to a self-employed filer — sourcing rules decide the answer instead.
How current is this?
The Illinois and South Carolina rules on this page were last checked against Illinois Department of Revenue and South Carolina 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.
- Illinois Department of Revenue — individual income taxaccessed 2026-08-07
- South Carolina Department of Revenue — individual income taxaccessed 2026-08-07