AFiling Status
Match the filing-status box on the return. For Married Filing Jointly, use the combined household amounts already shown on that joint return. This consideration supports Single and Married Filing Jointly.
Social Security · Input Guide
Help me fill out the inputs
Start with the same year's Form 1040 or 1040-SR for each return-based input. The highlighted lines below show where to look. These are the 2025 form's line numbers; older returns may show AGI on line 11 instead of 11a/11b.
1040
Income section · 2025
HYPOTHETICALIncome section · 2025
ILLUSTRATION
Simplified excerpt with fictional amounts. Select a highlighted line for its matching calculator input.
2aDTax-exempt interest$2,000
2bTaxable interest$0
5bTaxable pension income$30,000
6aBSocial Security benefits$40,000
6bETaxable Social Security$12,800
9Total income$42,800
10Adjustments to income$0
11aCAdjusted gross income$42,800
Line 11b repeats AGI in the Tax and Credits section. Unneeded lines are omitted here. This illustration is not a complete tax return or an IRS form for filing.
BAnnual Social Security Benefit → line 6a
Enter total annual benefits: $40,000 in this example. Use the amount reported on the return, rather than bank deposits after Medicare premiums or withholding.
CAGI → line 11a or 11b
Enter $42,800 in this example. AGI already includes taxable Social Security. Do not add line 6a or 6b again, and do not use taxable income from line 15.
DTax-Exempt Interest Income → line 2a
Enter $2,000 in this example. Enter zero if there is none. This interest affects how much Social Security is taxable, even though the interest itself is excluded from taxable AGI. Do not use taxable interest from line 2b.
ETaxable Social Security Already in AGI → line 6b
Enter $12,800 in this example, not the $40,000 total benefit. Leave blank to estimate if you do not know line 6b; enter 0 if you know none was taxable. The maximum is 85% of annual benefits, but the actual amount can be much lower.
Three different amounts—three different inputs
In the example, annual Social Security is $40,000, its taxable portion is $12,800, and AGI is $42,800 ($30,000 pension + $12,800 taxable Social Security).
Combined income for Social Security taxation is $30,000 + $2,000 tax-exempt interest + half of $40,000 = $52,000. The joint-filer formula makes $12,800 of the benefits taxable. Tax-exempt interest affects that calculation without being added to AGI.
The remaining inputs come from your plan
Planned Roth Conversion
Enter the additional taxable conversion you want to test. This is a planning amount, not a number to copy from the return. The AGI baseline should exclude this planned addition. If the return already includes a conversion, use a baseline estimate without that conversion and any Social Security taxability changes it caused.
Federal Tax Rate (%)
Use the federal rate assumption you want to test, or the linked case's estimator rate. It is not a tax-return line, withholding percentage, or total tax divided by AGI. Manual scenarios apply that rate only to newly taxable Social Security. When Social Security modeling is enabled in the main case and a federal estimator is applied, linked results instead recalculate federal brackets and deductions, including senior-deduction phaseouts. The displayed additional SS tax excludes direct tax on the conversion or IRA distribution.
Use Case Inputs
Links filing status, AGI, the conversion amount, and the federal rate to your current case. Update those in the main calculator, or uncheck this option to enter a separate scenario. When main-case Social Security modeling is enabled, benefits, taxable benefits, and interest also come from the case. Uncheck linked modes to try tax-return details, then use Apply These SS Inputs to Main Case to copy the baseline assumptions. The main calculation never automatically reads a separate manual scenario.
Include Projected IRA Income / IRA Income Age
Uses the case's retirement assumptions and gross IRA distribution at the selected age from its no-conversion ledger. The distribution is shown for reference and supplied automatically. Keep it out of baseline AGI so it is not counted twice.
If you only have part of the return
Ask for the income section showing lines 2a, 6a, 6b, and 11a, plus the filing status. AGI alone cannot tell you total Social Security benefits or tax-exempt interest. The optional taxable-benefit field can estimate line 6b, but the annual benefit amount is still needed.
Use the return as a starting point, then adjust for the year you are modeling. Keep benefits, AGI, interest, and any entered taxable portion consistent with that same baseline year. Special situations such as lump-sum benefit elections or repayments may require the IRS worksheet.