Calcufast

NIIT 3.8%: MAGI $250,000 + NII $60,000 (single) = $1,900

Net Investment Income Tax: 3.8% of the lesser of NII or MAGI over $200,000 (single) / $250,000 (MFJ).

The figures in the title are an example. Change the inputs to see your result.

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Inputs
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Results

Enter MAGI and net investment income.

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Net Investment Income Tax (IRC 1411)

IRC 1411 NIIT is 3.8% of the lesser of net investment income or MAGI over the threshold ($200,000 single/HoH, $250,000 joint).

NIIT

NIIT = 3.8% × min(NII, max(0, MAGI − threshold))

Hero example

ItemAmount
Filing statusSingle
MAGI$250,000
NII$60,000
Threshold$200,000
Excess MAGI$50,000
Taxable (min of NII, excess)$50,000
NIIT$1,900

Other scenarios

StatusMAGINIINIIT
Single$180,000$40,000$0
Single$250,000$60,000$1,900
Married joint$250,000$10,000$0

Thresholds (not inflation-adjusted)

StatusMAGI threshold
Single / head of household$200,000
Married filing jointly$250,000
Married filing separately$125,000 (not modeled here)

Related: paycheck take-home, additional Medicare.

Educational estimate

Not tax software and not CPA advice. Form 8960 details, MFS, and estates/trusts are outside this calculator.