Roth conversion taxes in Montana (2026)
By Mario Bailey · Published · Last reviewed
Montana taxes Roth conversions as ordinary income at graduated rates up to 5.9%. A conversion adds to your state taxable income in the year you convert, on top of federal tax. The table below shows the computed Montana tax on a $50,000 conversion at three baseline income levels, using 2026 rates.
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 | $987 | $3,937 | $2,950 | 5.9% |
| Single | $80,000 | $3,347 | $6,297 | $2,950 | 5.9% |
| Single | $150,000 | $7,477 | $10,427 | $2,950 | 5.9% |
| Married filing jointly | $40,000 | $84 | $2,809 | $2,725 | 5.5% |
| Married filing jointly | $80,000 | $2,219 | $5,169 | $2,950 | 5.9% |
| Married filing jointly | $150,000 | $6,349 | $9,299 | $2,950 | 5.9% |
Social Security and retirement income
Montana does not tax Social Security benefits. A conversion can still raise the federally taxable share of your benefits through the provisional income formula.
Montana simplified to two brackets (4.7% / 5.9%) effective 2024 per SB 399. Social Security fully exempt from 2024 per SB 112. Standard deduction includes $3,010 personal exemption per filer ($6,020 MFJ). Private pensions and IRA distributions are taxable.
FAQ
Does Montana tax Roth conversions?
Yes. Montana taxes Roth conversions as ordinary income at graduated rates up to 5.9%. Federal tax applies on top.
Does Montana tax Social Security benefits?
No. Social Security benefits are not subject to Montana income tax.
What is the top Montana rate on a conversion in 2026?
5.9% at the highest marginal rate.
Model your Montana conversion in the calculator
Rate data source: https://mtrevenue.gov/taxes/individual-income-tax/ (Montana DOR; two-bracket structure from SB 399 (2023) effective 2024; SS fully exempt per SB 112 (2023))