Finance category
Mortgage, loan, investing, tax, and money calculators.
NIIT Calculator
NIIT (3.8%) applies to net investment income for single filers over $200K MAGI or joint filers over $250K. Common hit: rental profit, cap gains at sale, dividends, interest. This calculator sizes the liability. NIIT thresholds haven't been inflation-indexed since enactment in 2013. Effective tax creep has pulled more taxpayers into NIIT each year. Strategies to reduce: increase tax-advantaged retirement contributions to drop MAGI below threshold, time capital gain realizations across tax years, use real estate professional status to recharacterize rental income as non-passive, or employ tax-loss harvesting to offset investment income.
NIIT owed
$2,660
Taxable base (lesser of excess or inv income)
$70,000
Total investment income
$77,000
MAGI excess over threshold
$70,000
Your threshold
$250,000
How the math works
Joint $320K MAGI: excess $70K. Total inv income: $77K. Taxable base = lesser = $70K × 3.8% = $2,660 NIIT.
Pay quarterly via estimated tax to avoid penalty. Strategies to reduce: REPS qualification for rentals, 1031 exchanges to defer caps, Roth conversions to reduce future investment income exposure.
How to Use
- Enter MAGI and filing status.
- Enter investment income components.
- See NIIT owed.
Frequently Asked Questions
Who pays NIIT?
Single/HoH: MAGI over $200K. Joint: $250K. MFS: $125K. Thresholds NOT indexed for inflation. Trusts/estates also liable over $14,450.
Can I avoid it?
Real estate professional status (REPS) — if you qualify, rental income is 'non-passive' and might avoid NIIT. Also: 1031 exchange defers the tax on gains. Retirement account income is exempt.
What counts as investment income?
Rental net, cap gains, dividends, interest, royalties, annuity income. NOT: wages, self-employment income, active business income.
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