Updated July 28, 2026. Quick answer: Treat it as taxable. We could not identify a broad retirement exclusion in Connecticut’s cited authority that would cover a conversion, so plan on the converted amount being ordinary income at the state level.
Confidence note: we could not locate authority granting an exclusion. Treat as taxable and verify.
Why a conversion is a different question from a withdrawal
Almost every state summary answers “how does Connecticut tax retirement income?” That is a question about distributions. A Roth conversion is not a distribution in the ordinary sense — it is a voluntary election to recognise income now in exchange for tax-free growth later. Whether a state’s retirement exclusion reaches that election is a separate question, and it is the one that decides your bill.
Where we cannot find authority for an exemption, we say so rather than assuming one exists. Verify with a Connecticut preparer before converting a large amount.
What Connecticut does with the converted amount
State income tax: graduated to 6.99% (6 brackets, 2%-6.99%)
How Connecticut treats IRA and plan income: Pension/annuity income: 100% deduction below the same $75,000/$100,000 AGI thresholds; deduction phases out above them, reaching zero at $100,000 (single) / $150,000 (joint) (phase-out replaced the cliff beginning TY2024). IRA distributions (non-Roth): deduction phased in — 75% for TY2025, 100% beginning TY2026, same thresholds and phase-out.
| Conversion | State tax at 6.99% |
|---|---|
| $50,000 | $3,495 |
| $100,000 | $6,990 |
| $250,000 | $17,475 |
Straight arithmetic at the stated rate. It ignores deductions, credits, and any graduated bracket effects, so treat it as the ceiling rather than a filing figure.
What to ask a preparer about Connecticut
Is there any exclusion I am missing that would reach conversion income?
Converting around a move
Converting in the year you move into Connecticut is the case that catches people. Residency at the moment of conversion is what generally determines which state gets to tax it, so a conversion executed a week before a move and one executed a week after can produce different bills.
Four separate taxes change when you move, not one: income tax on withdrawals, treatment of Social Security, estate tax, and inheritance tax. A state that looks good on conversions can be worse on the other three.
The state bill is the smaller half
Whatever Connecticut does, the conversion is federal ordinary income first. The federal bracket you land in, and whether the conversion pushes you over an IRMAA threshold two years later, will usually move more money than the state line does. The state answer tells you whether to convert here; the federal answer tells you how much to convert at once.
Paying the tax from outside the account matters more than either. Using converted dollars to pay the bill shrinks the balance that was the entire point of converting.
Sources
Authority: CGS § 12-701(a)(20); CT DRS 2024 CT-1040 instructions; CGA OLR Report 2024-R-0130; Conn. Gen. Stat. sec. 12-391(g).
Compiled from state statutes, session laws and revenue-department publications and adversarially verified in July 2026. Dataset confidence for Connecticut: high.
This page states what the cited authority says. It is not tax advice, and a conversion large enough to matter is worth putting in front of a preparer who can see your whole return.