This Roth Conversion NIIT Calculator page is built for users with investment income who want to see whether conversion income may create a net investment income tax review item.
The calculator can show a bounded 3.8% NIIT preview from user-entered net investment income and the calculator MAGI proxy excess, but it does not classify investment income or complete Form 8960.
Use the sample worksheet to understand the threshold interaction, then open the calculator and compare your investment income records, capital gains, K-1s, and Form 8960 context with a qualified professional.
Sample result preview
Investment-income NIIT review sample
The sample output highlights MAGI proxy before and after conversion, NIIT threshold excess, user-entered net investment income, and bounded 3.8% NIIT preview.
- Taxable conversion
- $70,000
- Estimated upfront cost
- $19,058
- Break-even year
- Year 3
- Modeled federal effective rate
- 27.2%
Sample assumptions
- $70,000 conversion
- $160,000 current taxable income
- $35,000 net investment income entered
- Single filing status
This is a fixed educational sample, not stored user data and not a recommended conversion amount. Change the calculator inputs before using any result for professional review.
NIIT worksheet preview
NIIT Bounded Estimate Preview
The taxable conversion adds $70,000 to the calculator MAGI proxy, moving the proxy from $160,000 before conversion to $230,000 after conversion. With user-entered net investment income of $35,000, the bounded NIIT exposure base is $30,000 and the 3.8% preview is $1,140.
- MAGI proxy before conversion
- $160,000
- MAGI proxy after conversion
- $230,000
- NIIT exposure base
- $30,000
- Bounded 3.8% preview
- $1,140
NIIT is generally 3.8% of the lesser of net investment income or modified adjusted gross income above the applicable filing-status threshold.
Missing review items
- Net investment income categories for Form 8960, such as interest, dividends, annuities, royalties, rents, capital gains, and passive activity income.
- Investment-income deductions and adjustments used on Form 8960.
- Modified adjusted gross income details rather than only the calculator taxable-income input.
- Whether any income is excluded from net investment income or belongs to a trade or business exception.
- Capital gain, passive activity, rental, and K-1 records that may affect Form 8960 review.
This NIIT preview is bounded and educational only. It is not a full Form 8960 calculation and does not classify investment income, deductions, trade or business exceptions, credits, or every MAGI adjustment.
This page is educational and illustrative only. It does not provide tax, financial, legal, investment, or Form 8960 advice.
This Roth Conversion Calculator is for educational and illustrative purposes only. It does NOT constitute tax, financial, legal, or investment advice. The calculation results are based on the information you provide and the latest IRS tax rules, which are subject to change. We do not guarantee the accuracy of the results. Please consult a licensed Certified Public Accountant (CPA), financial advisor, or tax professional before making any financial decisions.