Model both sides
The best planning answer often comes from comparing scenarios, not maximizing one deduction in isolation.
Free tax planning tool
Taxable Social Security and Roth Conversion Planner
See how a Roth conversion or other income can pull more Social Security into taxable income before choosing the conversion amount.
No account required Educational, not individualized advice
Taxable benefits before conversion
$20,450
39% of entered benefits
Taxable benefits after conversion
$44,200
$23,750 additional benefits pulled into taxable income
Illustrative federal tax on added income
$14,025
Conversion plus newly taxable benefits × selected marginal rate
IRMAA checkpoint: the proposed conversion changes income used in other systems. Compare the applicable official Medicare thresholds separately before acting.
Plan the conversion windowEducational estimate, updated August 23, 2026. Uses the Social Security combined-income worksheet thresholds and 50%/85% inclusion mechanics. It omits deductions, special exclusions, lump-sum elections, married-filing-separately lived-with-spouse rules, capital-gain stacking, IRMAA calculations, and state treatment.
How to use the result
Move from estimate to decision
Run alternatives, identify the assumptions driving the difference, and save the documents needed to validate the final treatment.
Check interaction effects
Income, deductions, credits, payroll, retirement, and state rules can move together.
Validate before filing
Use the result to focus review. Do not treat a screening model as a completed return.
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Core results are free and ungated. Share your contact information only if you want Taxstra to follow up about the planning questions this tool surfaced.
Frequently asked questions
The calculator is intentionally explicit about what it does and does not decide.
Can up to 85% of Social Security be taxable?
Yes. The taxable portion depends on combined income and filing status; 85% is a cap, not a tax rate.
Why include tax-exempt interest?
Tax-exempt interest is included in the combined-income test even though it is generally excluded from federal taxable income.
Does the tool calculate Medicare IRMAA?
No. The result flags that conversion income can affect Medicare income measures, but it does not calculate premiums or provide Medicare advice.