Clear Money Guide
What this state guide covers
A quick view of the questions, practical details and source notes below.
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Updated July 28, 2026. Quick answer: No. South Dakota has no state income tax, so converting to a Roth costs you nothing at the state level. Only the federal bill applies.
Why a conversion is a different question from a withdrawal
Almost every state summary answers “how does South Dakota 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.
This is the simplest case on the map. South Dakota levies no tax on ordinary income, so the entire question of whether a retirement exclusion covers a conversion never arises. Your conversion is a federal-only event here.
The planning consequence is the opposite of what people expect: because the state adds nothing, the timing question in South Dakota is purely federal — bracket, IRMAA, and the tax you pay from outside the account.
What South Dakota does with the converted amount
State income tax: none
How South Dakota treats IRA and plan income: Not taxed (no state income tax).
| Conversion | State tax in South Dakota |
|---|---|
| $50,000 | $0 |
| $100,000 | $0 |
| $250,000 | $0 |
South Dakota takes nothing, so this is a federal decision.
There is no state income tax, so a conversion costs $0 here whatever its size. That leaves the federal bracket it fills, the Medicare premium surcharge that keys off your income two years earlier, and how many years the Roth has to compound. Those are the parts that decide whether a conversion was worth doing.
Before you start, what actually happens. The form is run by Kapitalwise, our advisor-matching partner. Kapitalwise sends your details to advisers who pay for the introduction, so expect calls and texts. Clear Money Guide is paid when you submit the form, whether or not you ever hire anyone. This is free to you and there is no obligation to hire anyone.
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What to ask a preparer about South Dakota
Nothing to ask at the state level. Spend the question on federal timing.
Converting around a move
Converting after establishing residency in South Dakota is the whole play. People moving here from a taxing state sometimes convert before the move and pay a state bill they could have avoided entirely by waiting.
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 South Dakota 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: South Dakota imposes no personal income tax.
Compiled from state statutes, session laws and revenue-department publications and adversarially verified in July 2026. Dataset confidence for South Dakota: 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.
Nearby states
With no state income tax, the conversion is a purely federal calculation — enter a state rate of zero in the Roth conversion state tax calculator and it returns the federal bill and how much of the conversion lands in the Roth. If you are weighing a move to a state that does tax conversions, it will price the same conversion on both sides of the move.