Net investment income tax: 3.8% on the lesser of investment income or MAGI above the statutory threshold
One command in the Planning pack, available in the CLI, as an MCP tool and as a JavaScript import: planning niit.
What it needs, and why
Every input is checked before anything is calculated. magi and netInvestmentIncome are required; the rest refine the answer.
| Input | Required | The question it asks | Why it matters |
|---|---|---|---|
magi | yes | What is modified adjusted gross income for the year? | The tax applies only to MAGI above the threshold. |
netInvestmentIncome | yes | What is net investment income: interest, dividends, capital gains, rents and passive income, less related expenses? | The tax is on the lesser of this and the excess MAGI. |
filingStatus | optional | What is the filing status? | Thresholds are $250,000 joint, $200,000 single and $125,000 separate. |
Requests it answers
- “will they owe the 3.8% tax”
- “net investment income tax”
- “NIIT on this sale”
An agent with this pack loaded picks the command from phrasing like that, asks for whatever input is missing, and reports the figures with the method that produced them.
Limits it inherits from wealth-planning
- Bracket headroom uses only the standard deduction and ordinary-income brackets. It ignores itemized deductions, credits, capital-gain and qualified-dividend stacking, NIIT, IRMAA thresholds and state tax.
- RMDs use the prior December 31 balance. Use the Joint and Last Survivor Table instead when the sole beneficiary is a spouse more than 10 years younger.
- Monte Carlo assumes normally distributed annual returns and ignores taxes and fees.
The full pack, its other 4 commands and what it deliberately leaves alone are on the Planning page.