Roth conversion taxes in South Dakota (2026)
By Mario Bailey · Published · Last reviewed
South Dakota has no state income tax, so a Roth conversion costs you nothing at the state level: only federal tax applies. That makes the federal bracket math, IRMAA thresholds, and Social Security interaction the entire decision. The table below confirms the zero-state-tax result at three income levels.
Computed example: $50,000 conversion
State tax only (federal not included), age 66, standard deduction, no other state adjustments. Computed with the same functions the calculator uses.
| Filing status | Baseline income | State tax without conversion | With $50,000 conversion | Tax on the conversion | Effective rate |
|---|---|---|---|---|---|
| Single | $40,000 | $0 | $0 | $0 | 0.0% |
| Single | $80,000 | $0 | $0 | $0 | 0.0% |
| Single | $150,000 | $0 | $0 | $0 | 0.0% |
| Married filing jointly | $40,000 | $0 | $0 | $0 | 0.0% |
| Married filing jointly | $80,000 | $0 | $0 | $0 | 0.0% |
| Married filing jointly | $150,000 | $0 | $0 | $0 | 0.0% |
Social Security and retirement income
South Dakota does not tax Social Security benefits. A conversion can still raise the federally taxable share of your benefits through the provisional income formula.
FAQ
Does South Dakota tax Roth conversions?
No. South Dakota has no state income tax, so only federal tax applies to a conversion.
Does South Dakota tax Social Security benefits?
No. Social Security benefits are not subject to South Dakota income tax.
What is the top South Dakota rate on a conversion in 2026?
0%. South Dakota does not levy income tax on Roth conversions.