Tax & Payroll
Net Investment Income Tax Calculator (Form 8960)
Estimate the 3.8% NIIT on investment income when your modified AGI is above the threshold.
Preparing your result…
What this calculator does
Estimates the 3.8% Net Investment Income Tax.
What your result means
NIIT due on the smaller of NII or MAGI excess.
Formula
NIIT = 3.8% × min(net investment income, max(0, MAGI − threshold))
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- NII
- Net investment income
- MAGI
- Modified AGI
- • Tax year 2026 figures from IRS Rev. Proc. 2025-32 unless stated.
- • Statutory thresholds, not indexed.
Sources and review
Reviewed 2026-09-23 · Next review 2027-01-15
- • Does not determine what counts as NII.
- • Federal only — state and local taxes are excluded.
- • Rules change annually; figures apply to tax year 2026 only.
- • Educational estimate, not tax advice.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
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