1099 Contractor in Connecticut with a South Dakota Client: Where Do You File?
Answer
The client's state is irrelevant here twice over. South Dakota does not tax personal income, and even if it did, a client's mailing address does not by itself source your income to that state. Connecticut taxes the profit as resident income.
Last verified
Nothing is withheld from a 1099, so the tax that a W-2 employee never sees is money you are holding on someone else's behalf. In this pairing all of it belongs to Connecticut, and none of it to South Dakota.
What you file
- 1Quarterly estimated payments · Connecticut
Make quarterly estimated payments to Connecticut Department of Revenue Services — nothing is withheld from a 1099.
- 2Resident return · Connecticut
File a Connecticut resident return reporting your full self-employment income.
The two states, side by side
| Connecticut | South Dakota | |
|---|---|---|
| Taxes wages | Yes — graduated | No |
| Reciprocity partners | None | None |
| Convenience rule | Only against convenience-rule states | No |
| Nonresident return | Form CT-1040NR/PY | Not applicable |
| Credit for other-state tax | Schedule 2 (Form CT-1040) | No income tax |
| Nonresident safe harbour | None published | Not applicable |
| Local income tax | No | No |
| Revenue department | Connecticut Department of Revenue Services | South Dakota Department of Revenue |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in South Dakota and working in Connecticut gives:Client state only, 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: Connecticut → South DakotaHome state only
- Remote worker: Connecticut → South DakotaHome state only
- Moved mid-year: Connecticut → South DakotaOne part-year return — the state you left
Other Connecticut pairs
Questions people actually ask
I live in Connecticut and my client is in South Dakota. Do I have to file a South Dakota tax return?
The client's state is irrelevant here twice over. South Dakota does not tax personal income, and even if it did, a client's mailing address does not by itself source your income to that state. Connecticut taxes the profit as resident income.
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 Connecticut and South Dakota hold an agreement makes no difference to a self-employed filer — sourcing rules decide the answer instead.
How current is this?
The Connecticut and South Dakota rules on this page were last checked against Connecticut Department of Revenue Services and South Dakota 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.
- Connecticut Department of Revenue Services — individual income taxaccessed 2026-08-07
- South Dakota Department of Revenue — individual income taxaccessed 2026-08-07