1099 Contractor in Connecticut with a Colorado Client: Where Do You File?
Answer
Pay Connecticut by instalments, and watch your Colorado days. Reciprocity agreements do not help here: every one of them covers wage withholding, and a 1099 has no withholding to switch off. Connecticut taxes the full profit, Colorado taxes the on-site share, and the Connecticut credit reconciles them.
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 Colorado is measured in days on the ground rather than in invoices sent.
Colorado publishes no de minimis day count or dollar floor for nonresidents. Any Colorado-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 Colorado Department of Revenue — Taxation Division nonresident instructions before filing.
What you file
- 1Quarterly estimated payments · Connecticut
Make quarterly estimated payments to Connecticut Department of Revenue Services on your full self-employment income — nothing is withheld from a 1099.
- 2Nonresident return · ColoradoForm DR 0104 with Schedule DR 0104PN
File a Colorado nonresident return only if you performed services inside Colorado. Colorado publishes no de minimis day count or dollar floor for nonresidents. Any Colorado-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 Colorado Department of Revenue — Taxation Division nonresident instructions before filing.
- 3Resident return · ConnecticutSchedule 2 (Form CT-1040)
File the Connecticut resident return last and claim the credit for any tax paid to Colorado.
The two states, side by side
| Connecticut | Colorado | |
|---|---|---|
| Taxes wages | Yes — graduated | Yes — flat |
| Reciprocity partners | None | None |
| Convenience rule | Only against convenience-rule states | No |
| Nonresident return | Form CT-1040NR/PY | Form DR 0104 with Schedule DR 0104PN |
| Credit for other-state tax | Schedule 2 (Form CT-1040) | Form DR 0104CR |
| Nonresident safe harbour | None published | None published |
| Local income tax | No | Yes |
| Revenue department | Connecticut Department of Revenue Services | Colorado Department of Revenue — Taxation Division |
| Last verified |
The other direction
Reversing the commute does not always reverse the answer. Living in Colorado and working in Connecticut 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: Connecticut → ColoradoBoth states — credit offsets the double tax
- Remote worker: Connecticut → ColoradoHome state only
- Moved mid-year: Connecticut → ColoradoTwo part-year returns
Other Connecticut pairs
Questions people actually ask
I live in Connecticut and my client is in Colorado. Do I have to file a Colorado tax return?
Pay Connecticut by instalments, and watch your Colorado days. Reciprocity agreements do not help here: every one of them covers wage withholding, and a 1099 has no withholding to switch off. Connecticut taxes the full profit, Colorado taxes the on-site share, and the Connecticut credit reconciles them.
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 Colorado hold an agreement makes no difference to a self-employed filer — sourcing rules decide the answer instead.
How current is this?
The Connecticut and Colorado rules on this page were last checked against Connecticut Department of Revenue Services and Colorado Department of Revenue — Taxation Division 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
- Colorado Department of Revenue — Taxation Division — individual income taxaccessed 2026-08-07