Estimate the immediate federal and state income-tax impact of a Roth conversion by applying your marginal rates to the portion of the conversion you expect to be taxable. A traditional IRA conversion can be partly or fully included in gross income; nondeductible basis can reduce the taxable share. This tool is designed for scenario testing before a conversion, especially when you want to compare conversion sizes. It does not calculate bracket stacking, the pro-rata basis calculation, credits, Medicare premiums, or other tax interactions.
1. Enter the conversion amount
Use the amount moved from a traditional retirement account to Roth.
2. Estimate the taxable portion
Use 100% only when you expect the entire conversion to be taxable.
3. Enter marginal tax rates
Use rates that apply to the incremental conversion in your scenario.
4. Review the tax estimate
The result applies the entered rates to the entered taxable share.
5. Run multiple sizes
Compare smaller and larger conversions to see how sensitive the estimate is.
This simplified model assumes the entered rates apply to all taxable conversion dollars. Actual U.S. federal tax is progressive, and IRA basis rules can change the taxable portion.
The IRS generally includes the taxable part of a Roth conversion in gross income for the year of conversion; the conversion itself is not subject to the 10% early-distribution additional tax when properly completed.
The main result is the incremental income tax estimated from the conversion inputs, before considering other tax effects.
For a real filing decision, calculate basis and bracket effects using current tax forms or professional advice.
Given
Calculation
Taxable amount = $50,000 × 1.00 = $50,000. Estimated tax = $50,000 × (0.24 + 0.05) = $14,500.
Result
Estimated conversion tax: $14,500. Conversion amount less modeled tax: $35,500.
This treats 29% as a flat incremental rate; an actual return may place different portions of the conversion in different brackets.
Traditional IRA basis from nondeductible contributions can make part of a distribution nontaxable. The actual taxable share generally requires applying IRS basis and aggregation rules.
A properly completed conversion is generally not subject to the 10% additional tax at conversion, although taxable conversion amounts are included in income. Later distributions of converted taxable amounts within a separate five-year period can have additional-tax consequences.
This calculator does so as a simplified estimate. State rules vary, and federal bracket interactions can make the actual incremental rate different.
No. Higher income can affect Medicare premiums, credits, deductions, and other items; those are outside this model.
You can model the tax cost here, but using retirement funds to pay tax reduces the amount reaching Roth and can create separate distribution issues. Consider cash-flow and tax advice before doing so.