1099 Contractor in South Dakota with a Connecticut Client: Where Do You File?
Answer
Connecticut only, and only for on-site work. Nothing is withheld from a 1099, and South Dakota levies no income tax, so the single question is whether any of the services were performed in Connecticut. If none were, no Connecticut nonresident return is required.
Last verified
The most common contractor worry — that invoicing an out-of-state client creates a filing obligation there — is usually unfounded. What creates the obligation is physical presence, and South Dakota residents have no home-state return in any case.
Connecticut publishes no de minimis day count or dollar floor for nonresidents. Any Connecticut-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 Connecticut Department of Revenue Services nonresident instructions before filing.
What you file
- 1Nonresident return · ConnecticutForm CT-1040NR/PY
File a Connecticut nonresident return only for income from services you physically performed in Connecticut. South Dakota does not tax wage or self-employment income.
The two states, side by side
| South Dakota | Connecticut | |
|---|---|---|
| Taxes wages | No | Yes — graduated |
| Reciprocity partners | None | None |
| Convenience rule | No | Only against convenience-rule states |
| Nonresident return | Not applicable | Form CT-1040NR/PY |
| Credit for other-state tax | No income tax | Schedule 2 (Form CT-1040) |
| Nonresident safe harbour | Not applicable | None published |
| Local income tax | No | No |
| Revenue department | South Dakota Department of Revenue | Connecticut Department of Revenue Services |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in Connecticut and working in South Dakota gives:Home state only — estimated payments.
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: South Dakota → ConnecticutWork state only
- Remote worker: South Dakota → ConnecticutNo state income tax on your wages
- Moved mid-year: South Dakota → ConnecticutOne part-year return — the state you moved to
Other South Dakota pairs
Questions people actually ask
I live in South Dakota and my client is in Connecticut. Do I have to file a Connecticut tax return?
Connecticut only, and only for on-site work. Nothing is withheld from a 1099, and South Dakota levies no income tax, so the single question is whether any of the services were performed in Connecticut. If none were, no Connecticut nonresident return is required.
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 South Dakota and Connecticut hold an agreement makes no difference to a self-employed filer — sourcing rules decide the answer instead.
How current is this?
The South Dakota and Connecticut rules on this page were last checked against South Dakota Department of Revenue and Connecticut Department of Revenue Services 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.
- South Dakota Department of Revenue — individual income taxaccessed 2026-08-07
- Connecticut Department of Revenue Services — individual income taxaccessed 2026-08-07